How Soon After Surgery Does the Pocket Close Not Allowing an Implant to Drop?

Breast implants after breast augmentation do not move. Swelling in the soft tissues around the implant artificially supports volume similar to bra. As the swelling goes down the implants don't move but the volume of the implant is redistributed in a more natural fashion. This may take three months.

    I would continue to follow your surgeon's instructions as there is a risk to vigorous massage causing suture line compromise at the inferior aspect.  Kenneth Hughes, MD Los Angeles, CA

As the implants settle, they don't actually move. Submuscular implants are sitting as if they are at the bottom of an envelope. The breast fold, like the bottom of the envelope keep the implants from descending. At the upper pole is a large space under the muscle and above the ribs, and that space goes up to the clavicle (collar bone). Typically the implant position looks fine at surgery. As the patient awakens, the relaxed pectoralis muscle contracts, pushing on the implant. This displaces the silicone (or saline) which bulges into the upper pole, the only direction with room to expand. The lower pole of the breast may seem to empty out. But the implant itself doesn't actually move. As the muscle relaxes over several months, the upper pole no longer bulges , the lower pole of the breast fills out, and the implant position looks like it did in surgery.

Best advice is to follow your own surgeons instructions. No one on line knows you, knows what was done, nor has followed your progress. 

All the best.