Make the SM kit before the first rehearsal, then bring it to all reahearsals. It's mostly a first aide kit, but is also an all-purpose have-everything-on-hand kit. (Not everything on this list is necessarily. Pick and choose which things you want.)
Spike tape
Gaff tape
Stop watch/timer
Pens/pencils GALORE (actors steal them)
Maglight
Leatherman
Tape measure (carpentry)
Tape measure (costume)
Highlighters
Hole punch
Glue stick
Stapler
Paper clips
Scissors
First aid stuff:
Bandaids
Aspirin/Tylenol/advil
Cough drops
Vitamin C
alcohol wipes
pads/tampons
ice packs
hydrogen peroxide
condoms ;)