Using Fat Distribution to Shape Body Early T

Hello, I (19) was just a tad underweight before T and now I'm 3 months on T only a few pounds heavier. Fat distribution has begun a bit as I've been trying to gain weight which has all gone to my upper body and I've also lost some fat in the thighs. I really want to lose the fat in the ass but that area doesn't want to go yet. Of course, I know changes to my body will be happening over the course of years but I'd still like to work on my body where I can. Losing a lot of weight isn't an option since I'm still underweight so I'm thinking of gaining weight then losing weight again? Has anyone else encountered this and was able to get rid of that ass fat? Is it still too early to try to shape my body?