Pinch Hitting Question

[eirenical]

So... I didn't sign up to pinch hit because this is my first Yuletide, but I was scanning the list and see a prompt that I'm fairly certain I could fill without undue stress. Does anyone know if I can claim it even if I'm not signed up to pinch hit? Or to find out if it's already been claimed?

Or should I just not bother and write it up as a treat? ;)