It's a gamble for you to make. HRT might make your body hair virtually vanish, like it did with many. It might do nearly nothing, like it did with many. It might leave you with most of your body hair, but lighten it in such a way that laser wouldn't be very effective on it, like it did with me. (Codename: Owned.)
Do women in your family generally have a relatively large amount of hair for women? That might be a clue. If so, then maybe yours won't be reduced all that much. If not, then maybe you'll get lucky. I have a feeling there's a genetic factor in how much "basic" hair one has and how much being a guy changes.
But for facial hair... HRT having a significant effect on it is a rare, surprising occurrence, generally seen in people whose facial hair hasn't fully developed yet. So you shouldn't bet on it. For your face at least, get laser early on.