YES!! You totally should! And you would do it for you not for her. Because when you disclose to her about your stutter, she would obviously know that you stutter and you would know that. So when you stutter the next time you'd be more comfortable because she knows what's going and your mind wouldn't go into thinking how uncomfortable she is. The way that i would do it is: Hey ___ I just wanted to let you know that I have a stutter and need more time to say what I want to say. Don't say ut in an appolegetic manner because that makes the other person view you negatively. Say it in a neutral informative manner, this is how i talk and this is what I need. Studies have proven that when stutterers disclose in that manner people view them more positively