I for the most part wait a little before telling people (not just for dating). Just because saying "I'm bipolar and on psychotropic medications" doesn't really sound so great on a first date lol. Let them get to know you for awhile that way they're not making judgement before they even get to know you :P. Though my last girlfriend knew I was bipolar before we got together and knew a lot of the stuff I have gone through... but yet still ended up dating me for a year and a half.