OK - Let's say you have "done your homework" and made a penciled list of 5 teams your DD has decided she'd like to try out for. This list is prioritized - #1 being most desirable, #5 the least. Since it's rare she'd be lucky enough to have the tryouts in order of priority (#1 first), you can still make a priority based decision.
If team #2 is your first tryout, why not take an "on the spot" offer? If she finds that this team "stinks", there's always next year.
Team #3 is a coin flip. (Again - always next year)
Teams #4 & #5 is where I'd wait for a shot at #1, #2 or #3 before making a hasty decision. But instead of sitting around waiting for the team tryout, I'd suggest calling the coaches of #1 & #2 and ask for a private tryout. If she REALLY wants to play for her #1 choice, it's worth the effort.
It's not Rocket Science, but the people that have the most problems with this are the gamblers. Always waiting for something better to come along - waiting on a phone call that may never come. Last in line are guaranteed to get the leftovers.