I was on HRT while in the Army. What I would recommend is that you wait until all of your training is over and you're at your first duty station. Once you're there you have 2 options. You can talk to your primary care doctor about being transgender and it'll be in your military record. The other option, when you have personal time see a provider outside of the military and pay out of pocket to begin HRT. I paid out of pocket to begin HRT while I was still in the Army, later on I did inform my doctor that I was on hormones, but I was already being medically retired. They can't remove you for being transgender right now, but I know the Army could remove a solider early on under a failure to adapt chapter. It may be safer to pay for hormones out of pocket until they clarify the laws on them, you're also going to want to wait until you get to your duty station because they run a lot of blood work on new service members up until that point.