I'm new to this site completely, but you guys seem really wise here.

So I just started T a few days ago - a little less than four days, maybe eighty-something hours ago - and within day one, I noticed my voice was scratchier. And now, by day four, it's not necessarily sounding male, like having the male scratchiness and deepness, but I've noticed that I can't talk in the part of my throat that I used to be able to talk from. It's really uncomfortable if I do so. So I have to talk lower/deeper.

My two friends who have already started T (both on about 7 or 8 months) said that didn't happen for weeks. So am I just an early bird? Or are they late? Because you hear about voice drops and cracking at about three or four weeks in, not three or four days...

I mean I'm not complaining, this is awesome. But it's just a little weird.

I've also instantly noticed muscle development, and I haven't worked out at all. My dad is pretty muscular naturally, he's a bear of a guy, so maybe I just got the lucky genetics and T is working fast for me?

Yes, the same thing happened for me. I noticed changes the same night and the next day, changes in sleep, changes in voice, changes in muscles within a week or so.

In my case right before I was signed off for T I tested as low on female and male hormones in the blood work. I figure the speed at which T started affecting me might have had something to do with there being very little to counteract it, hardly any estrogen in my system. My body seemed to respond immediately. 

I had elevated T levels pre-everything which seemed to help speed things along. Within the first week I was getting the scratchy voice thing like you are and body hair was starting to fill in.

The voice started to get lower and scratchier within two weeks. It didn't start to stabilise until around 6 months on T; when before one day it'll sound low and almost male and another it would sound pretty much like my old voice.

Same here. My voice dropped very, very quickly. Like you, I experienced a weird scratchiness in the first couple of days and, by the end of the second week, it had majorly dropped. It continued dropping and leveling out for the next four months or so before it stopped. Though it took a long time for me to gain the mid-range back (It was either baritone or soprano with a sad, raspy breath between), it's finally settled.