Why on earth would you race off and start practising songs that you played in a previous band?
 
	 
 
	If you're doing this properly you don't leave anything to chance. You don't start your homework until you get a set list, keys, YouTube videos, MP3's or verbal information regarding the source material and the arrangements of every song. It's unprofessional to turn up to a rehearsal without knowing all of those things.
 
	 
 
	In my experience an unprofessional rehearsal means an unprofessional band and for me that puts the whole gig in doubt.