[This is a very personal decision and there are no wrong choices and your gender is real no matter what you do or don't do, and if you change your mind that's real too; all things are possible when you understand you never deserve adverse consequences, internal or external, for Doing Gender Wrong.]
DO IT.
My personal rubric for making a big but not time-sensitive decision is that if I've been "should I or shouldn't I"ing for months or years, that means I want to do it. I simply do not think that way about things I actually don't want to do. I suspect you're similar.
Also, as a practical consideration, the process is slow as hell (both procedurally in getting through the healthcare system, and in that the effects of HRT are gradual), so if you start now you'll have plenty of time to back out if it feels wrong, and if you wait until you're 100.0% ready to do it today, you'll be frustrated that your appointment to get an appointment to get an appointment has a waiting list.
(Also, some doctors and jurisdictions that are kinda but not extremely trans-hostile will let you continue HRT, but will make it very hard to start, so if right now you're somewhere that it's not hard to start, that's a consideration.)
There's never going to be a perfect time. But any time that you're financially and legally able to medically transition is a good time.
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(One note on HRT being gradual: in my experience the two not-easily-reversed changes that do set in pretty fast are voice change and lower growth. Both of those don't hit their final form for awhile, but they can be noticeable within the first couple months. I would temper my advice if either of these is something you have significant reservations about.)
