New South Wales
Just to show the above is correct, here's where it's covered in the rules:
RRG - Deployment wrote:
Red, blue, and yellow deployment points are not
active until specified by the mission’s rules, even if another
rule allows a one-time deployment to any of those points.
Thematically, the one-time deployment isn't spawning characters out of the ground. They were always there. The Rebels just didn't know they were there until the triggering event occurred. X marks the spot, essentially.