K.K.
Hi! I had one of those as a kid, and while it's never fun, it definitely does get better. I can't give you a specific timeline, but my guess is that within a week it really stopped bothering me. It seemed to me that the first few times I turned it, it was quite painful (basically teaching your palette bones to spread apart), but after that, the bones seemed to move very easily. In retrospect, I'm very glad I had one because I had a very small upperjaw. Hopefully you'll find it's worth the pain and trouble. Good luck!