Back in my "father" years, I was regularly buying new bras in different sizes for my two daughters for about 14 years. Considering they are 6 years apart in age you can do some simple arithmetic and see that each one took more than 6 years before they achieved a stable chest size, or in one case, simply moved out on me and began buying her own bras. We will not develop any faster than a natal female will even with megadose horomones. We reset and start a clock when we begin taking them, but you do not do two months of growth in a single day with one E shot.
At a bit short of 4 years on E, my breasts have developed to the point where my doctor ran a mammogram on me and found suspicious tissue in one. A needle biopsy later, and we find it was benign fibrous tissue, but I was afraid of losing my breast at the rate some people wish to grow them.
You have caught me in a somewhat wry moment on the subject.