I may have a problem.

I had the first chapter of my novel online when I queried. No one ever commented on it until after the book sold, at which point my agent said I should probably take it down, since the chapter/book might change in edits.

I sold the book before I got the agent, so had we gone on sub together, she might've requested that sooner. (My previous agent did.)

Look up the history of John Scalzi's Old Man's War. After that, look up Orson Scott Card's history of posting his work in advance on his Hatrack River site. There's no hard and fast rule.

The deciding factor is how much the publisher wants your book. A secondary consideration is how many copies of it they think they can sell, and whether they think you've compromised some fraction of those sales. I can't speak for every publisher. Some are twitchier about it than others.