It depends on what is faster, but I will probably will be parked and leveled before a motorhome, TT, or Fifth wheel can back into many spaces. That is, if they can get in the space at all. If it is a level pull through, I don’t do anything other than stop and put the slides out. Probably the same in a class A, but I see TTs and fifth wheels put stabilizers down.
I can certainly be leveled before the manual jacks complete going down even if they are using a drill. Besides, from what I’ve seen, people still level the wheels on a TT and fifth wheel and tongue before putting their jacks down.
I rarely put my jacks down for stabilizing unless the wind is really going at about 30-40 mph. TTs and fifth wheels rock a lot more. Probably can get by without stabilizing with a Class A as well.