My first signs were downstairs. After a day or two, my junk started to...twitch. I guess it was already growing a bit, but it never grew all that much. My second sign was horniness. Five days in (my existing T level was low, so maybe that's why it took that long), I woke up with a raging lust. Unfortunately, I was scheduled to meet my therapist in a few hours, and I already had the hots for him. That was interesting, to say the least.
I also noticed that I was lubricating. For my entire adult life, I have had a problem with dryness down there. Not anymore.
I think after that, my throat started to tickle. My voice went down a bit in the first month, but subtly--I could tell, and my therapist could tell, and some of my trans friends noticed, but most people didn't hear the shift. (Of course, it kept dropping, but I didn't make it into baritone range until nearly eighteen months after I started.)
I did have a surge in aggressive and competitive behavior pretty quickly. I've always been pretty passive, but I found myself wanting to get ahead in traffic and win friendly arguments with my best friend. It took me quite some time to get that under control. I'm much better now.
My appetite did not change, but I was eating a lot of meat because of food sensitivities. Since then, I've noticed that I get hungry pretty quickly when I haven't had enough protein. So unless you're a vegetarian, eat your meat!
Most of my buddies started getting acne almost immediately. That didn't happen to me. In fact, my facial skin didn't start getting noticeably oilier right away, maybe because I've always had severely dry skin and eczema. Now my skin is tougher. My nose, forehead, and chin are oilier. But all of that took quite a while to happen.
For most of my friends, the first month brought increased appetite, increased sex drive, increased acne, a tickly throat, and a small voice change.