First and foremost what is progressive overload, it's just mean progression over a long duration of time and consistency through discipline. There many way you can increase progressive overload load, increasing the weight each week (example 1kg), doing an extra rep, having a slower tempo ( mechanical tension on the eccentric motion), increasing time under tension, it just slight progressive over time. For example if your bench 80 for 8 reps, 35 second set, and go to complete failure. Then the followering week you bench 80kg for 9 reps for 40 second set. That is a form of progressive overload. It's will also depend on your diet/genetics/cutting or bulking phases on how quick you progress each week. The best way to track progressive overload load is by writing down your sets/reps/duration into a long book and try beat it slightly each week over a long duration of time.

If you have severe muscle pain or delayed onset muscle soreness in a major muscle group, it mean that you have put stimulus/progressiveoverload into the muscle from hevey resistance training. You should allow your muscles atleast 72 to 96 hours of rest before working them again in my option to allow them to make a full recovery, if of course you are looking for optimal muscle growth. Remember muscle are building through recovery, so if they are extremely sore you should allow them to rest and make a full recovery. This is why I recommend upper, lower spilt or push, pull and legs spilt, this allow you to rotate each muscle group. So while your chest is resting, you are hitting legs for example. It tough in a fitness class, because you are doing circuit exercises, you will have to make your own mind up in that situation, if you feel like you need another day of rest from being exstemly sore you should skip it imo, if you feel like it's only a little sore then maybe you should be fine. It's all come down to your own perspective and how you feel that day.

I personally find you can get addicted to pre workout, then you start to rely on it every time your train, best thing to do in my opinion, when it come to pre workout, I have it on my very hard hevey day (hevey compounds), maybe 3 to 4 times per week. As if you have it each day, you can build a tolerance/rely and start using more each time to get the same effect. If you like pre workout, shop around for some mild caffeine ones/no stimulus, if your feel like it's overpowering you.