I told only my bf. I dated before him but nothing serious and no one I ended up having interest in after few dates. I told him probably a three weeks in. Honesty is important yes. Giving the person time to get to know the real you is important too. If you drag it out too long it could seem like lying through omission, to me anyways. I would only tell though if I am seriously interested, if I think the person is going to be around for quite a while.

My b had NO knowledge of Bipolar except for one episode of ER he saw, so haha it didn't leave him with a good impression. But I explained it to him and how it affects me. It opened discussion and he had his own illness to tell me about.