I try for around 1k. Often my first chapter will be a little shorter as I try for a more dramatic punch with less exposition so the story will unfold. As a reader if a novel's first chapter goes on like my old aunt Betty prattling on and on I don't read more of it. It seems like too much filler.
All that said, however, I really favor a "natural" break. Sometimes if you've only got about 500 words but everything feels complete, then do that. We've all read something where we've paged ahead waiting for the point. And, we've all read something that was longer but was so well put together we didn't notice the length.
Write hard, write true.