First changes from my personal experiences:
Psychological - but that was just by knowing you get your T - so it was just a placebo effect:
happyness all over. Getting shot for the first time was like an initiation rite for a boy in a tribe. I had to fight for it for a long time, with myself and with the shrinks, and it does not hurt much but syringes freak me out as hell. Wow, I'm finally gonna grow up now physically. Okay, I was grown up before, but as a female, and to me this just felt wrong, not grown up.
After 2-3 days:
libido increases like hell
you start smelling like a guy
In my case, it was in mid-summer, so that was very confusing and somewhat unpleasant, but okay.
After 1 month:
First beard hairs appearing at my chin. (two or three)
First hairs appearing on the inner side of my thighs.
First shy hints at a happy trail appearing.
Hairs on my underarms getting more pronounced.
Voice dropped further down suddenly, throat aches, bad control of my voices. (had some drop down of voice before after I got off from female hormones one year before T, my natural hormone levels are in-between male and female)
libido still very high
After 3 months:
Further voice drop
Fat redistribution on my face
More hairs on my chin, happy trail, inside of thighs, underarms.
Muscles started building up.
Muscles hurt and made weird things (cramps etc.).
Started to have an ambiguous passing: butch lesbian/14-year-old boy. (Before: almost no passing.)
libido still very high.
Etc.
