Most studies I’ve come across talk about 6-18 months.

Here’s one - https://www.google.com/amp/s/www.pcf.org/news/18-month-adt-optimal-for-locally-advanced-prostate-cancer/amp/

I have not seen three months.

While I did not do ADT in conjunction with SRT, I did when SRT failed and I had four pelvic lymph nodes show up on a C11 Choline scan.

The treatment plan was originally 24 months of ADT in conjunction with 25 radiation treatments and six cycles of taxotere.

We stopped at 18 months of Lupron because of my positive response to treatment, been three years since, no treatment required so far.

Normally I believe while on ADT you want to see your T below 50, prefers less than 20.

You may want to discuss with your medical team why three months, what is the basis for that, why not 6-18 months. You may also want to discuss your T level, the impact of nite being below 50, better yet, 20.
Kevin