Why does Gatsby insist he doesn't want to put Nick to any trouble by having him invite Daisy over?

Gatsby wants Nick to arrange for the meeting at Nick's house because it would be inappropriate for her as a married woman to meet with Gatsby at his house. Nick's house is also more convienent because it's neutral and Tom or others wouldn't question her being at Nick's house. Finally Gatsby wants the "big reveal" of his house. If things go well at the initial meeting he can then casually invite them over to his house where he can reveal his success to Daisy as he has been hoping to ever since he got out of the Army and began building his fortune.

Gatsby wants Nick to arrange the meeting with Daisy because he was her Cousin so her husband was going to approve the invitation and also that Gatsby knew that Daisy wanted material things so he wanted to catch her in a surprise showing her what he had attained as well as getting her back.