Welcome!
There's no "right" order to start things, but I'd say you have two areas to focus on - one getting yourself ready, and one gathering what info you can from others. See who else has info of anyone else involved besides the actors - designers, technicians, etc, for the same contact sheet. Also, has anyone started a calendar?
As for yourself, go back through the script and start making yourself a breakdown of whatever is helpful to you. Props, scenery, costumes, sounds mentioned. Go back again through and work on a scene breakdown for actors - or even just yourself to tab out the script for what locations are which scenes. These two items will be most useful to then after you start working with everyone else and you'll have a decent handle on the show itself. I often have those two things at least in rough format before I actually start communicating with the director. He/she may have their own breakdowns (yay! - better to just see if you have the same things), but again, you'll know more what you're discussing.
And continue to poke around here for lots of ideas.
Good luck!
Erin
