The nectarine flowers can be damaged by cold weather and cold winds which will hinder the flower forming a fruit. Be prepared to keep a 'weather eye' and cover the tree with burlap or other material to protect the delicate flowers. Once the fruit forms you should thin/cull. Depending on the variety of nectarine the fruit could be ready anywhere from June/July to September.
Hope you take lots of photos so we can watch as the tree grows.