can i safely turn on my heat with my water not turned on in my house
I'm no expert, but if your heating system is composed of hot water radiators, I would NOT turn it on until your water is on. 

From what I know of these systems, even if they don't require new water to run, they still need to be plugged to the water system for when they need it. 

For instance, right when you start to use them at the beginning of the cold season you need to bleed your radiators, which means you open a small valve and let the air come out. 

Your system will need water to replace that air.