take off the master and hold it in a vice or what ever, manually push in the piston all the way to the bottom, before letting it out put your fingers over the the outlet holes and release the piston, this will create a vacuum in the cylinder sucking the fluid into the cylinder. Do this a couple of time to prime the master then refit.. note: this will be messy and can squirt out a long way if you are not ready for it,, have water around to flush any brake fluid split and make sure you don't squirt it on any paintwork.
always start bleeding at the left rear bleeder working your way up to the front.