Lori, NRT is an abbreviation for "Nursing Resource Team" it's essentially the new term used for a nursing float pool within a few hospitals around the GTA (not sure if it is widely used elsewhere).
OP - start times may differ from unit to unit. However I have typically heard of day shifts starting at either 0700, 0715 or 0730 so it would be safe to assume something within that time frame. Since you got the job it doesn't hurt to ask. Call HR or call the clerk on the unit explaining you are a new hire and would like to know. Good luck and congrats on the job!