memo, Rabbonim say that if someone has an illness they shouldn’t say right away, only let the other person know after a few dates when they have a sense of who you are and you have a sense if they can handle the information. Of course if you have a serious illness, it wouldn’t be fair to the other person not to disclose it to the shadchan and to work with a Rav and a shadchan who know how to find the right shiduch for you.
In addition, in many cases if you have a past history and you have turned your life around, many Rabbonim say that you don’t have to disclose this either until you get to know the other person a little so they judge you on who you are today and not who you were when you were much younger. If your past was not revealed when the investigated you, then waiting a few dates according to the Rabbonim will not make a difference. Some Rabbonim according to another thread hold that you don’t have to disclose this information at all. I disagree because when your spouse finds out after marriage, or your chosson or Kallah find out after engagement, it can bring about disastrous results.