Saxman911:
My experience (layperson) has been that regular PSA results report in about 24 hrs; Ultrasensative PSA (uPSA) can take a few days.
The reports include information on the equipment used and sensitivity levels of detection (fine print below).
Quest labs is fine. I was tx'd at Johns Hopkins in Baltimore and offered to return from Pennsylvania for PSA testing, and Rad Onc said that I could go to Quest locally (have 2 local hospital systems available also, but Quest had better connectivity to JH for ordering tests and reporting results).
What is important is to use the same lab for consistent reported results.
And I have 2 friends being treated who also had PSA measured shortly after tx; not sure why. My Rad Onc was uninterested in results prior to 6 mos post radiation. Just FYI.
PSA after radiation therapy should continue to fall until you reach a low point or nadir.
Best wishes.

At Mayo, test results come back in about 30 mins.