I would just fill it, check for leaks, shock it (at least 10 ppm dichlor), run all the systems (each pump/zone/diverter, check heater, ozone, etc), and check for leaks again. Chlorine is effective at any temp, so you don't have to wait for it to heat up. Let it sit for a couple of hours to make sure the chlorine has time to kill anything it finds, check the chlorine level add more if necessary, run everything again, then decide based on how much stuff came out of the pipes, if it looks like Swirl Away is necessary before draining. (In Phoenix, the tub may already be up to temp by the time this is all done.) Drain, clean the filters/install new ones and refill.