Indications for timing of breast reconstruction vary on a case to case basis.

Ultimately, the decision whether to undergo immediate or delayed breast recosntruction depends on patient preference.  Certain factors, such as advanced  tumor stage and the need for radiation therapy, tend to favor delayed reconstruction to optimize oncologic and aesthetic outcomes.

There is sufficient data to support the fact that a woman's breast cancer prognosis is not negatively affected by the timing of breast reconstruction. 

There are of course advantages and disadvantages to both immediate and delayed reconstruction.  However, most plastic surgeons feel that all things being equal, a  better cosmetic result can be achieved with immediate reconstruction.

Immediate breast reconstruction (at the time of mastectomy) has several advantages; it saves a surgery, the aesthetic results are better, there are psychologic advantages as well. Some complications, wound healing and infection rates are slightly higher with immediate reconstruction.

There are times when immediate reconstruction is not feasible and delayed would be better. Not everyone is a candidate for this. You and your surgeon will decide this.