How long should it take?

[Steve Cole]

I am doing a LS swap and my motor has sat for 2.5 years. (I know) I changed the oil pump, water Pump, and every seal and gasket I could. I also replaced the oil pan so pretty much all the oil was removed from the engine. I attempted to build oil pressure today- I disconnected the coils and the fuel tank is bone dry. I tried cranking over the motor while watching a oil pressure gauge I connected. The needle never moved. I motored it multiple times, 5-10 seconds at a time. The needle never moved. They say to prime the oil pump when you have install it but I can't remember if I did that. So my question is, how long should it take to build oil pressure under these conditions?
Any suggestions what I should do?
Thanks!