My voice started changing within days of my shot. It was very subtle. At first I thought it was from the cold I had, but a) my voice had never sounded like that from a cold before and b) it stuck around after I got better.
It's been a very gradual lowering. After a couple months, I'd have never noticed if I wasn't keeping track.
My voice has gone a bit lower than an octave from my starting point. Singing, Pre-T, I was mostly G3-D5 in range. I'm now E2-F~A3 in usable range. If I sing a bit everyday, I can get a solid D2. Falsetto I'm G3-B4 (again, usable singing range). I have a lot of trouble with my head voice so my upper range is iffy atm.
All that said, I'm having a lot of issues with my voice overall, so that might affect my range. Hoping to see a speech therapist soon... just waiting for an opening now...