My head is starting to peel today. I haven't shaved since Friday and am worried that I'm gonna have to start over. How long does it typically take for it to be safe to shave again after a sunburn?
I never wait myself. I just go ahead and shave!
As long as you can tolerate the pain it is OK. You can always clipper shave if a blade is painful.
Like Slybeard said, it will be whenever your skin can take the blade without being in too much pain. I think, though, that if you are peeling already, the top layers of skin probably are dead and will not be feeling much of anything.