How are Jn 7:6-7 and Jn 15:18-19 reconciled in so far as they speak of the world's attitude towards the disciples?

In John 7, He was speaking to His unbelieving brethren, not his disciples.

John 7:1-8 ESV [1] After this Jesus went about in Galilee. He would not go about in Judea, because the Jews were seeking to kill him. [2] Now the Jews’ Feast of Booths was at hand. [3] So his brothers said to him, “Leave here and go to Judea, that your disciples also may see the works you are doing. [4] For no one works in secret if he seeks to be known openly. If you do these things, show yourself to the world.” [5] For not even his brothers believed in him. [6] Jesus said to them, “My time has not yet come, but your time is always here. [7] The world cannot hate you, but it hates me because I testify about it that its works are evil. [8] You go up to the feast. I am not going up to this feast, for my time has not yet fully come.”

His disciples on the other hand DID believe in Him.

John 15:18-19 ESV [18] “If the world hates you, know that it has hated me before it hated you. [19] If you were of the world, the world would love you as its own; but because you are not of the world, but I chose you out of the world, therefore the world hates you.

The target audience in both sections is different.

Audience # 1

John 7:6-7 is addressed to “His brothers” (v3) who “did not believe into Him” (v5).

They distinguish themselves by telling Jesus about “Your disciples” (v3).

Obviously they are the unsaved part of the evil world. So the world cannot hate them.

The difference is that Jesus “witness”es “about” the world, “that its works are evil” (v7).

Audience # 2

In contrast, John 15:18-19 is addressed to His disciples “who were His own” and whom “He loved to the very end” (John 13:1).

These, His own, are the people “who left houses, or brothers, or sisters, or father, or mother, or wife, or children, or lands, for the sake of” Jesus’ “name” (Mat 19:29).

Obviously, these are the people who denounced the world for Jesus. So the world hates them.

In John 7:6-7, Jesus speaks to His brothers, who at that time did not believe in Him (John 7:5) - specifically, they did not believe that Jesus was the Messiah.

However, Jesus' brothers James and Jude later became significant leaders in the early church. As such, they would have been subject to the world's hatred, in accordance with Jesus' words in John 15:18.

Josephus records in Antiquities 20.9.1 that Ananus the high priest condemned James and others, leading to their execution.

https://gutenberg.org/files/2848/2848-h/2848-h.htm#link202HCH0009

1. And now Cæsar, upon hearing the death of Festus, sent Albinus into Judea, as procurator. But the king deprived Joseph of the high priesthood, and bestowed the succession to that dignity on the son of Ananus, who was also himself called Ananus. Now the report goes that this eldest Ananus proved a most fortunate man; for he had five sons who had all performed the office of a high priest to God, and who had himself enjoyed that dignity a long time formerly, which had never happened to any other of our high priests. But this younger Ananus, who, as we have told you already, took the high priesthood, was a bold man in his temper, and very insolent; he was also of the sect of the Sadducees, 23 who are very rigid in judging offenders, above all the rest of the Jews, as we have already observed; when, therefore, Ananus was of this disposition, he thought he had now a proper opportunity [to exercise his authority]. Festus was now dead, and Albinus was but upon the road; so he assembled the sanhedrim of judges, and brought before them the brother of Jesus, who was called Christ, whose name was James, and some others, [or, some of his companions]; and when he had formed an accusation against them as breakers of the law, he delivered them to be stoned: but as for those who seemed the most equitable of the citizens, and such as were the most uneasy at the breach of the laws, they disliked what was done; they also sent to the king [Agrippa], desiring him to send to Ananus that he should act so no more, for that what he had already done was not to be justified; nay, some of them went also to meet Albinus, as he was upon his journey from Alexandria, and informed him that it was not lawful for Ananus to assemble a sanhedrim without his consent. 24 Whereupon Albinus complied with what they said, and wrote in anger to Ananus, and threatened that he would bring him to punishment for what he had done; on which king Agrippa took the high priesthood from him, when he had ruled but three months, and made Jesus, the son of Damneus, high priest.

John 7:6-7 and 15:18-19 do not contradict one other. Together they reveal the reality that the world does not hate unbelievers; it hates believers because their holy lives 'testify that the world's works are evil (John 7:7).'

The Jewish leadership, especially the Sadducees, sought to arrest Jesus outside the temple area before the crowds surrounded him. They had a problem of how to identify Jesus. When it was Jesus' time, they resolved this by getting Judas to point Jesus out in an isolated place to arrest Jesus.

See Why didn't the Jewish leaders try one more time to have Jesus stoned to death?

"The Jews" vs. "the Crowds" in John 7 - a distinction with an important difference?

What does "My hour" mean in John 2:4?

In John 4, why does Jesus say he was not honored in his own country yet he was welcomed?

In John 8:59 was picking up stones more of a threat to express their distain or a real danger?

In Luke 24:16 why were the disciples eyes kept from recognizing Jesus, then opened?

Also the account about Zaccheus (Luke 19) told the crowd around Jesus once he was identified.

Apparently, the Jewish leadership were trying to identify Jesus through identifying his family. Jesus had already mentioned that a prophet is not honored in his hometown. Those in his hometown willing to identify Jesus would not confront Jesus directly but would confront his family to get Jesus to go to Jerusalem with them. Jesus went to the temple in Jerusalem in such a way that he wasn't identified before he got there. After Jesus' crucifixion identifying Christians wasn't an issue with persecution. See Acts for example.

"My time" it was not yet Jesus' time to be arrested and crucified. It was the time for Jesus' family to go to Jerusalem.

And after these things Jesus was walking in Galilee, for He was unwilling to walk in Judea because the Jews were seeking to kill Him. Now the feast of the Jews, the Feast of Booths, was near. Therefore His brothers said to Him, “Leave here and go into Judea, so that Your disciples also may see Your works which You are doing. “For no one does anything in secret when he himself seeks to be known openly. If You do these things, show Yourself publicly to the world.” For not even His brothers were believing in Him. So Jesus said to them, “My time is not yet here, but your time is always here. “The world cannot hate you, but it hates Me because I bear witness about it, that its deeds are evil. “Go up to the feast yourselves; I am not yet going up to this feast because My time has not yet been fulfilled.” Having said these things to them, He stayed in Galilee. But when His brothers had gone up to the feast, then He Himself also went up, not publicly, but as in secret. (Jn 7:1–10, LSB2022)