On the past 6 months, I've stopped 3 times cold turkey and restarted after about 2 weeks of stopping. Last time I stopped, I was beginning to form buds. Took a lot of counseling and affirmation to settle things on. It is not easy, for sure.
I was very concerned that it would impact my progress, but the buds are still growing and at least in my own perception, there is steady progress. Buds are growing and so are my nipples changing into a female shape, I think they are between an A/B cup. Thighs, hips are growing and waist is shaping as well. So I think there was no impact other than delay the changes a bit.
I think I am at what would be 3-4 months of progress, from what other sisters report in their timelines. That is when usually the changes "kick in" (Onset of breast formation and increased fat redistribution). Also my doc increased my dosage to the standard level now, so I expect changes to increase further from now on.