From my experience I would disclose this information only when I was certain this turned into sth serious and if we are to be in relationship he would need to know the truth. I would give hints as we go along. That's what happened to me. I met a guy, much much younger, I was keeping it very casual and distanced but he was just going more and more crazy about me. First I confronted him with a question about what he thinks now of prostitutes (it was more a discussion that basically led to this question being asked by me)saying I used to have a friend who had no other choice but work as an escort. His answer suggested that he is ok with that but wouldn't be entirely happy if I did that. Though he would understand if I chosen that profession as a last resort.
I basically kept bringing him closer and closer to the business,mentioned I rent flat to working girls.
Then I was away abroad and he called me asking who is "My Working Name" I didn't answer and disconnected and then he messaged all links and pictures he could find. We had a talk and he said he suspected it since the first hint. So he basically did the math and he knew the truth. I told him I wanted him to find out, If I didn't then he never would. I also told him that now he knows we can be a proper relationship and he is very happy boy now. Me too as I no longer have to hide everything from him and it made my life so much easier! He also helps me a lot ,clean the flat,stays with kid when I tour. Everything just changed into better and my feeling for him too:-)
My advice is to keep it secret until you know it can turn into a serious relationship. Only if he loves you he will be able to put up with it. If you tell him on a first date then he either judge you straight away or keep you for a free sexual encounters. But if he doesn't know about it,he will want to get to know you for who you are deep inside and not for what you do.
Best of luck with your dates hun!
x