I've always been paid within 90 days after the editor grades the report.
That said, I don't count on the money for paying my regular bills or my budget for mystery shopping.
If you have the time to do a shop with them, willing to put in the time for the reports; I would recommend the company based on my own experience. If you need the cash quick as a bunny, this is not your company.
I consider the payments as Yippie! money. My last paycheck, I was able to buy some landscape trees that were clearance.
Live your life in such a way that when your feet hit the floor in the morning; the devil shudders...And yells OH #%*+! SHE'S AWAKE!