I’m concerned about rippling and lateral displacement (Photo)

Right now, you are fine. You don't have a lot of tissue to cover the implants, so the edges show when laying down. This is expected. You might wear underwire bras to minimize the implants moving more to the sides until well healed.

There are many reasons this may happen; usually these include poor dissection with excessively large pocket, placement of too large of implants, not performing a breast lift when indicated, and gravity (exacerbated when placed with too large of implants).

The surgical technique chosen by your plastic surgeon will impact significantly the amount of rippling and amount of lateral displacement.
Two ways to reduce the risk of rippling. - Location of the implant: Putting the implant under the muscle will significantly reduce the chance of rippling as the pectoralis major muscle will cover the top portion of you implants which is where the rippling mostly happens. - Nature of the implant: Saline implants are much more prone to rippling then Silicone implants. The new generation silicone implants are very cohesive which limits how much they ripple.
Two ways to reduce the risk of lateral displacement: - The dissection of the implant pocket should be very minimal laterally and generous medially so that a patient can achieve a perfect cleavage. - Wear the surgical bra religiously the first 2 weeks, and then a sports bra for 6 more weeks so that the implant pocket scars perfectly. The normal force of gravity will pull the implants down and lateral, you don't want that to happen before your pocket scars in completely.
Hope that helps, goodluck.