I usually tell my patients that it takes about 6 weeks to have a good idea about what the buttocks will look like. If at that point it appears that there has been absorption and/or you would just like to be bigger, then you need to wait at least 3 months from the surgery to have a second fat transfer. I do not believe that squatting will result in loss of volume.
Doing squats at this point should not reduce your volume, but it will probably also not improve it either. Within 3 months after surgery you can have an idea of further need for autologous fat grafting. Appropriate garmenting at this point is probably your best bet for improving your results. Best wishes. Daniel Golshani, M.D., Beverly Hills.