I've put my brakes back together and connected it all up, now I'm trying to bleed them. The system was empty when I started and I'm getting very little fluid through the bleeder. Was getting zero fluid for a while and now getting a small trickle if I hold down the lever. I imagine there was a lot of air in the system as there was no fluid, and the master cylinder is draining as I pump the brake lever, so I assume fluid is getting in the system, but I'm not sure if I'm doing it right, having never done it before. Is it normal for an empty system to take forever to start pumping out fluid? If so are there any tricks to make it easier, like holding the lever closed for a couple hours? Thanks in advance!