How Long Does It Take for Pectoral Muscle to Loosen After Breast Implants?

It is still relatively early after surgery and I would not describe the difference as drastic. Discuss the use of preferential breast implant displacement exercises.

You are still fairly early in the post-op course.  You should give this at least 4months or more to settle in.

I agree with my colleagues and, as usual with Dr. Rand. The appearance of your right breast and the history is highly suggestive of either a fluid (seroma) or a blood collection (hematoma). This is best evaluated with an Ultrasound and may need to be surgically evacuated.
I regret to tell you but the appearance of the breasts will not markedly improve. Although gravity will draw the implants inferiorly somewhat, the overall result would not be optimal. A major reason in my opinion was the attempt to stretch the indications for a Benelli Lift way beyond what it was designed to do in your case to spare you a vertical scar. The Benelli operation was designed for MINIMAL lifts and when used with implants to do so with implants NO larger than 250-300 cc. The operation was NEVER designed or proposed to be a replacement for Breast Lift procedure involving a vertical scar (Lollipop, inverted T etc) when they are needed. When large implants are used with a Benelli Lift (where a donut of skin is removed around the nipple complex and the outer edges of the wound are stitched to the inner edge of the wound), the tension on the wounds results in puckering, as you demonstrate, and eventually in a "Star Burst" scar appearance.
You should see your surgeon about the right breast.
Good Luck.