The time for the second stage of the tissue expander/implant breast reconstruction does vary with each individual patient. Basically, after the last tissue expansion, your plastic surgeon is awaiting an ample time for your body to take advantage of the expansion performed by allowing the pocket to be created/matured via the construction of collagen and elastin. 3 months is a typical time for the body to adequately create this pocket. Today, with the use of acellular dermal matrix (e.g., AlloMax, AlloDerm, etc.), the time frame has been shortened since they act as a scaffold for tissue ingrowth. 6 weeks is the least amount of time that I would await prior to the exchange, but I have also waited 4-6 months prior to performing the 2nd stage. On average 6-12 weeks is a typical time in my practice.