When did you tell your partner?

I’m seeing someone I really like and I want to be honest, but I’m so scared of judgement. It doesn’t help that I recently told someone about my bipolar and was hit with ‘oh all psychos have bipolar’. I hate the media’s portray of this hell. I’m doing well atm, I’ve met someone but not told him yet. I’m so scared, how and when did you tell your partner? Any advice?