So I was job hunting recently (in the UK) and I disclosed it during the application process every time. People are quite accommodating and for one I even said: "I have a stutter that flares up in unusually high pressure situations like interviews. I can still talk to people just fine, but if I am being graded on my answer to something it's easiest if I can write it down."  Ask for what you need. If all you need is them to know, then let them know. I find it helps me relax in formal conversations.