It can take a little time for a game to fill up and get started sometimes, yes. It has been my experience that standard games tend to fill up pretty quick after 2-3 people have signed up though, and once a game is filled they generally will get started rather soon.
We would need to clarify to be 100% sure, but if you want remove yourself from a game that you've signed up for, I'd suggest emailing the GM for that game, or making a forum request asking for such.
- Josh