How long does it take for the muscle to stretch and accommodate the implant? What can I do to help stretch out the muscle?

Sounds like you had both a breast lift and a breast
augmentation on both sides. You may have needed more skin tightening on one side
than another which can make a difference in how you feel between the two breasts
postoperatively. Both of muscle and skin have to stretch to naturally to 
accommodate the implant. Much of this happens within 3 weeks but you should have
a good idea of what they will look like by three months. It is important to do
gentle range of motion exercises with your arms so you don't stiffen up. Follow
your surgeon's advice about possible massage. I often recommend a warm soft
washcloth on the breast at this point to soothe and soften.

Thanks for sharing your concerns with us.It takes approximately 2 months for the implant properly fits under the muscle. In my practice, after performing a breast augmentation i recommend to my patients to limit the movement of the arms for two weeks. After that, you can move your arms taking care and always with common sense. In this regard, it's not advisable to carry weight to prevent the implant out of position, and allow the formation of the physiological capsule around the implant, also to avoid pain and breast swelling.To talk about the last result of your surgery we need to wait at least 4 months. Kind regards,Dr. Emmanuel Mallol Cotes.-

It takes six months to a year for the implants to completely soften and seek their natural position. In the interim you can control the placement with smooth implants by using a superior band or /and tight bra. If you have smooth implants massage can help when your plastic surgeon suggests. Check with him and good luck...