Unless there are solos or other discoveries in your score study, suggested order is most likely to be:

Snare
Bass
Crash
Triangle
Sus cym
Timpani
Bells


My reasoning is that snare, bass and crash are the core and keep your band together. The color aux instruments are unique and generally easier to play if your section lacks depth. Timpani and bells are the hardest IMO because of pitch. Timpani is more unique than bells (usually doubles wind parts) so I don't staff the bell part unless we have a large section or a hotshot mallet player. Identify your section's skills and adjust. Snare player needs to be consistent regardless of sight-reading level.