The benefits of having the recontruction at the same time are a better cosmetic result (the majority of the time) and an overall happier patient. Multiple studies have shown that patients who have the reconstruction done at the same time experience less depression and have greater satisfaction, as they always have a breast.
In addition, a skin sparing mastectomy can be performed if the reconstruction is done at the same time, which means a shorter scar for you. This being said, in some situations it may be better to delay reconstruction. Tumors that are inflammatory in nature, that have ambiguous borders, or that grow into the chest wall or are intially metastatic past the lymph nodes may be good reason for delay.
If you need radiation post-operatively, your plastic surgeon may also want to consider delay depending on the type of reconstruction you choose together.
