Do you tell a new partner before the first outbreak or wait until it happens?

Started seeing someone a few weeks ago and I have not had a cold sore around them yet, but I know one is coming eventually, it always does. Part of me wants to just mention it casually now so it is not a big deal later, but part of me feels like I am making it a bigger thing than it is. How did you handle this, did you bring it up early or wait until you had to cancel a date at the last minute?