Initial PET Scan - how long for authorization?

For those of you diagnosed with IBC, how long did it take for your initial PET scan to be authorized by insurance?

My partner's oncologist is trying to rush authorization, but I'm not sure what that means to an insurance company given that it has been a week with no word. She has a large mass in addition to inflammatory features + lymph node involvement, so I wouldn't think there would be a whole lot of question as to the necessity. (Her primary care physician seems nervous that they haven't scheduled the start of chemo already, but obviously, the details of treatment depend on the scan.)

Thanks!