We do the same warm-up at every meet. I usually change it around a little bit from season to season and sometimes even during the season if I'm not happy with it.
We have a set warm-up routine that lasts for about 15 min. If the general warm-up at a meet is longer than that, I have the girls do line-drills, beam routines, floor dance and basic tumbling too.
Every exercise is done in such a way that you can use an 8-count rhythm and the running drills are done 8 times each or down the length of the floor (whichever makes more sense). The warm-up is choreographed so that the girls always know how to move from one exercise to another and they don't just change positions. Also, there are exercises that just focurs on form (drills for arm/hand form and position and foot form) in there.
First we do running drills with arm circles, chassés, high knees, and some jumping drills.
Then we move to stationary exercises that use a combination of active flexibility and passive flexibility. We do leg swings in all directions (some drills lieing on their backs or sides and some drills standing up), some active shoulder flex and some passive, warm up wrists and feet/achilles, do some core conditioning (mostly holding shapes) and finally move to handstands (drills and holds).
edited to add: During off-season I have them do the meet warm-up once a week but before the first meet I have them do it more often in order for them to get more confident with it.