I had a hair transplant, didn't run gear for about 2 years. so I don't have any experience right after the transplant but I would definitely edge on the side of caution for the first year and a half. Allow the follicles to settle and mature
After the two years (timing had nothing to do with the hair surgery) I run pretty much any gear (I want): Test, Masteron, ment, tren, primo, Anadrol proviron (these are my favorite compounds) as long as I run a high dose of RU twice a day my hair has stayed safe I've even been able to recover more hair than I had 2 years after my transplant.
But I use RU religiously, cycle rogaine on and off (due to slight effects it has on skin) and use a ketoconazole shampoo every time I shower.
If you find that a regiment like this doesn't help, from the research that I've done testosterone along finasteride is a good choice, because testosterone by itself isn't too bad but when it converts to dht, where we see more hair problems.
Deca anavar are supposed to be relatively hair safe . I don't like deca because of deca dick and if you run finasteride deca becomes less of a great option.
Surprisingly superdrol is supposed to be hair safe as well (even female safe in low doses). However, in the most recent time I ran it my hair was thinning out daily while I was on it. I say this with a caveat as I do question the quality of the SD that I ran.
From the compounds I've tried Halo (and probably SD) is the only one I won't touch again because of past experiences on hair.
I don't know if anybody else gets this but my head gets itchy when I start to lose hair it's a good barometer if my hair system is working lol