This has always been a frightening thing for me. I waited about two months into my current relationship so I could assess my boyfriend's attitudes/possible attitudes to mental illness. I even began a few conversations on the subject to test the waters. If he said anything really ignorant and derogatory I would have ended it. I agree that it is good to wait a bit so he will see who you really are above and beyond bipolar. If things progress well and you are sure you are really into each other then acceptance on his part should be easy. If he can't accept then he's no good to you.