The hormones will have their effect on the soft tissues of your face: the fat will redistribute and the muscles will atrophy a bit. Also the facial hair will diminish and hair to the scalp will become denser and thicker. All this will make your face look softer and more feminine.
Dr van de Ven will try to make your face as feminine as possible and there is no negative effect to your face becoming even more feminine after your FFS due to the hormones. Those last changes will be very subtle. Therefore Dr van de Ven does not see a reason to postpone FFS if you have only started taking hormones recently.