Re: when is the right time to.....
I do think it is an important thing to discuss with someone within say the first five dates or so. I say this only if you think or have a sense early on that this person you are dating has potential for an exclusive or long-term relationship (I realize you don't always know early on but as soon as you have the sense that it could be a viable relationship, I think it is necessary to tell them). Persumably, they like you for who you are and should be understanding. If they are not understanding (say, one of those rare types who have never experienced depression or have had any exposure to mental illness, mild or extreme, who think you can just "snap out of it") they either need to make a commitment to being educated or make a break because they will not come to terms with BP behavior or side effects from perscriptions, etc. which may cause problems in the long run.
I actually did not divulge my BPII diagnosis with my current boyfriend but was working up to letting him know when one day he admits to me as being BPI and medicated for it. It was a bit suprising to each other because we are very high-functioning individuals and didn't suspect it of each other. Now, we are finding out that two BPs can make for a difficult relationship but we are working on it every day. We are about a month and a half into this and I can't imagine it would have worked out if we had not have shared this information with each other.