Hi phoenix. And welcome.
Love your username. In fact, that is what I prefer to be called now instead of my at-birth name. I think you are doing the right things and I try not too over-think these things but it is good to be prepared.
I am sorta in the same boat you are(even down to the age part, cause people say I look about 10 years younger too). T will help us look kinda older and therefore help masculinarize our appearance even more, which is what I'm sure you want, right?

I say you are off on a very good start because you are taking appropriate steps for transitioning(in truth,there are a diversity of steps since all transsexuals/transgender people are unique

). I honestly just came out to my own self as being transgender last month and to my immediate family(unfortunately I was outted by someone to a sister I do not like much and another sister that I dislike but not with as much intensity...my oldest bro probably knows now too, which really frightens me to think about because he is also very religious/conservative/Christian, I believe

).
To make a long story short, everyone received it very well except my family(my favorite sibling, another big brother of mine, seems to try to accept it but I can greatly sense his discomfort when bringing it up in our text

). Even with highly supportive family, this sudden news can indeed be a shock or even devastating to hear about. Hopefully they will hear it from
you and not someone else behind your back. So do be careful who you choose to come out to, ok? I am quickly learning this and new things about this very hard pre-transitioning stage every single day.
Best of luck to you, my friend.