Thank you for your question. The answer will vary depending on whom you ask as surgeons often have different protocols postop. Best to check with your surgeon specifically. In my practice, I have my patients get fitted in specific underwire sports bras and ask the patient to wear them 24/7 for 2 months. This may change a little depending on the type of surgery performed as well. Good luck.
When I do breast augmentation surgery, I have my patients wear a bra for the first week to help re-establish the fold under their breasts. After that week the implants are resting high up, so I have them sleep without a bra to allow the implants to drop. It's always best to check on your surgeon's protocol. For more information on this and similar topics, I recommend a plastic surgery Q&A book like "The Scoop On Breasts: A Plastic Surgeon Busts the Myths."