Sit down with the musical director and choreographer and see how you three can work out a schedule to rehearse blocking, song, orchestra and dances successfully.
Organize a calendar about two to three months out from opening night. Schedule the rehearsals by keeping in mind that the first day of rehearsal is traditionally a read through of the play. If time permits, practice a couple of ensemble songs. Dates for "off book," technical rehearsal, dress rehearsals and opening night are pivotal to the schedule of the rehearsals.
Create a clear and informative calendar for all actors, technical crew and parents. Schedule the rehearsal from act one to the final act on Monday through Thursday with weekend rehearsals, as you get closer to the opening night, for technical and dress rehearsals.
Place importance on lead actor's scenes in the scheduling. Emphasis on the leads occurs after you have completely blocked the show. This includes singing rehearsals with orchestra rehearsals.
Go over the master schedule with the musical director, choreographer and technical crew. Check to see that the schedule works with your production team. If it does, make copies and pass the schedule out at the first rehearsal.