Write,
Having dated a fair number of men very casually before settling down with my now b/f for the last year, I would say that there is no reason to discuss your health issues until he has earned the right to hear about it by gaining a closeness that would warrant it.
At our age (I think I'm a bit older than you), almost everyone is on medication for something--be it high cholesterol, hormone replacement, high blood pressure, herpes, ad's, whatever. Some of those conditions are life threatening, some are contagious, and some are just the annoying problems of aging. What is worse, hearing that someone has had a heart attack, followed by by-pass surgery; hearing that your date has a contagious STD, learning that your date is a recovering alcoholic, or learning there is a psychological condition which is controlled with the proper medication? I don't know. Each individual will react differently to this kind of information, but if we want to find perfection in our 50's, then we better give up and learn to live alone. (you are the only perfect person you will find

).
I think there is the proper time and place for the sharing of this information. I agree with the others that establishing that the individual is worthy of more of your time should be done before baring your soul. I think if a connection is going both ways, he would at least be willing to listen and try to understand. If he is not, then he is not worth any more of your time and move on.
As far as the vulnerability signal goes--when we decide we will begin dating again, we all become vulnerable at some level, or we can never let someone else into our lives. Learning to be careful and smart about HOW MUCH vulnerability to expose is the tricky part. For me, that meant keeping things casual and friendly until I had had enough time to see him in a variety of situations, see him relate to his children, hear about his work history and get a sense of his past relationships and why they were in the past. Obviously, this takes time and the need to maintain some emotional distance so passion doesn't get in the way of common sense.
I hope some of that helps a little.
Brigid