30 minutes is correct. You can probably manage with 20, but anything later than that and you kid's slot will probably be given to a standby. They also go from the signup/meeting location to the JTA stage about 10 to 15 minutes before actual show time.I believe the child needs to arrive 30 minutes before show time but it might be a shorter window.
It's usually about 2/3 of the way through. If you watch JTA enough (like us thanks to DD5) you'll get to know the script and can anticipate when that part will occur. Timing it for your kid though is near impossible because you have no idea how the Jedi Master's helper is going to order the kids once on stage.Does anyone know how they choose the young jedi that will in addition to battling vader, also encounter the storm troopers?
Use the force on them to be exact,... I seen them only pick one child per showing...
any idea on how they select?