Presuming I am not handing out a written pop-quiz when they walk in, it is usually as follows:
Students start with some static stretches when they arrive, or after they finish the pop-quiz.
I might have someone lead the stretches or they do it on their own.
Then we do either [1] yoga & pilates, [2] calisthenics & shadow boxing (aka "tactical aerobics") or [3] kettlebells depending on my mood.
I often verbally quiz them about terminology, history, concepts etc while this is going on.
Then we work out
Bull rings, drills, techniques, countering/throwing lines, principles/concepts, grappling, randori, boxing, kickboxing, whatever
I might pick anyone to teach or demonstrate something, even a purple belt
Then we pay respects and talk story
Occasionally, students arrive late (which is fine by me - "Come when you can, leave when you need to.") so they warm up and stretch on their own and jump in when they are ready.
We are very informal; we only wear uniforms when we are going somewhere or when I suspect people have forgotten how to tie their belts...
Sweatpants and t-shirts with tennis or wrestling shoes most of the time.
I almost always "wing it" because I am never sure who will show up until everyone arrives.
We do not have split classes; there is no "beginner" or "advanced" class, everyone trains with everyone else.
I try to "average out" the material I cover to give everyone something to work on, regardless of rank, experience or relative skill.
It gives the seniors a chance to help teach and coach the under-belts as well - which is a good way for me to gauge their real understanding of the material, IMO.
My standing roster is only about 12 students so "averaging" is not too tough.