I don't try to hide it because if she's the one for me then she wouldn't mind that I stutter. I usually reveal it during a good mood like after telling a joke and she laughs. There's really not a specific time. Just tell the other person when you feel comfortable. I usually let the other person know within the first 30 minutes. For me, whenever I tell the other person that I stutter, they are usually really curious and ask me more about it. After I reveal it to them, the rest of the date flows extremely well and I stutter less because I am way more comfortable and so are they. Just don't your stutter affect your state of emotion and you'll be fine. If they judge you then they aren't meant for you. Good luck!