I am very upfront but I still always waited until the second date. I figured if it didn't work out and there was no second date they didn't need to know my personal business. But a second date can lead to a third and so on so I figure I might as well be upfront and let them decide whether to continue.

For what it's worth I never had anyone freak out when I told them or say they couldn't date me because I was bipolar. I did have several ask if I took medication, how often I got manic, general explanation of what bipolar is etc.. but no freak outs or being dumped because of it so that was good