Congrats! It is great you are getting in before your birthday too.
Changes are different for everyone - I started T last month and so far I have noticed oiler skin (acne already, ugh), my voice seems a little rougher but that may be in my head, and I think my libido has increased a bit. I'm also convinced that my thighs have dark hair coming in that didn't use to be there.
People have reported the first voice drop happening at around the first month point, but some people take much longer than that. It also depends on your dosage and the method of T you are taking. It may take a year+ for it to completely settle.
Take lots of pictures and record your voice. You may not notice small changes until you compare them side by side.
