ADT or SRT first after BCR

Very frustrating I'm sure. I'm not sure what I would do with conflicting advice like that. Maybe speak to the RO and ask why their recommendations are less aggressive than surgeon?

Do both

Everyone is different but 6 months should be appropriate.

The original question suggests that no ultrasensitive PSA testing is being done after RALP. This means there is no baseline below 0.1. The use of uPSA allows testing at much lower levels, resulting in a baseline that involves numbers, not less than symbols. When this is done, SRT can be initiated at lower levels. How low is still under discussion. My urologist is pointing to 0.1 as his preferred threshold for treatment.
Since at these levels the ability to find the cancer cells is not yet apparent, the radiation would be given in the area around where the prostate once was.
Note that there is residual PSA after the surgery, so the nadir (in uPSA) is looked for--the lowest point.* My nadir so far was at 16 months (below 0.006 on my particular uPSA.) Some research keys on the doubling rate of PSA, not just the absolute levels.
Historically, since testing was limited to 0.1 on the standard PSA, treatment was typically initiated at 0.2.
Since radiation causes damage, the goal is to administer it at the right time, when it will make a difference, neither too soon nor too late. *I guess with standard PSA testing, the nadir is the flat line below 0.1 from beginning to end.
ADT is used (in this situation) as an adjunct to enhance the effectiveness of the radiation (kind of a 1 + 2 punch), but studies have varied as to whether it makes a difference, how long to use it, etc. Alternatively, it may be used later, after the radiation is no longer suppressing the cancer, until the time when ADT no longer suppresses the cancer either.
And of course, radiation has a growing impact on quality of life (poop, piss, and passion ;-). ADT has an immediate impact on passion and hormonal balances, affecting muscle mass elsewhere as well. (So far as I know, it doesn't affect pooping and pissing much--women seem to be able to do these things with much less androgen.) For these reasons, there is concern to only use what is needed (both ADT and SRT,) while still slowing the cancer.
And yes, I said "slowing" intentionally. These are treatments to slow the cancer, not to cure the cancer. Of course, some people think positive thinking makes a difference, and this may lead them to act like slowing may be curing ;-). And that's wonderful! (Note my positive thinking there?!)

James1951:
I was answering the general question in general.
I recently completed Salvage radiation together w/ 4 mos ADT; as recommended by my Rad Onc at Johns Hopkins.
My understanding is that for BCR: Moderate risk cancer recommendation is Radiation and 4 - 6 mos of ADT.
High risk cancer recommendation from a recent authoritative study is Radiation and 18 - 24 mos ADT.
My cancer was G 9, which would be high risk, however my ADT recommendation was 4 mos (did not have decipher analysis).
Listened to, and trusting, my Rad Onc.
Lower risk cancer recommendation may be Radiation only.
As others have noted, there are a number of schools of thought, and many different recommendations.
Best to all to manage these challenging decisions.

I did 6 months Lupron and 70 Gy. radiation
35 sessions. 2020….my PSA since then has been 0.00

You mentioned that “ High risk cancer recommendation from a recent authoritative study is Radiation and 18 – 24 mos ADT.” I would like to read that study if you have the reference.

RADICALS-HD is the study that supports longer ADT for high risk (I think).

37 txs IMRT to whole pelvic floor (25 of the txs also included the pelvic lymph nodes) 66.6 gy.
1st post tx PSA @ 6 mos from radiation of radiation scheduled for Nov 15.
After RP, PSA .19 (confirmed .18).
Praying for undetectable in Nov (and beyond).
Will update with results.

Good luck with this……..always. Your urologist probably told you to expect aPSA rise then it should slowly come down. Best of luck with pending results.