nk235, does your fuel system leak? If not, you probably don't have an air leak.
You have not mentioned what the fuel flow was like when you bled the secondary filter (the 2 micron filter at the engine) with the lift pump.
Sometimes, when the lift pump starts to lose performance, the engine will be slow to start at first but on subsequent starts it will fire right up. Until it has a chance to sit and lose the prime again. Once fuel is flowing to the high pressure pump it will draw fuel on it's own. On older engines, the bottom of the lift pump had a weep hole that would leek if the pump diaghram went bad. CG regulations outlawed those types of pumps so now the system is closed and won't leak or draw in air that kills the engine when the pump is bad.
I'll go along with what's been said earlier. If your lift pump is working (you get good strong squirts when bleeding from the banjo on top of the filter) and you are getting clear fuel when bleeding, there is probably nothing wrong and the slow starting is normal for the season.
For the record. I would still prefill the Racor. If you don't, all of the air volume in that filter will have to be bled at the secondary, with the lift pump which does not have much flow volume. If you are concerned about air in the fuel lines during filter changes, either install valves or mount the filter in a slightly elevated position so the fuel doesn't run out of the hoses when you drain the Racor bowl.
Most of my fuel system is mounted below the top of the fuel tank. Before I open the fuel system I just make sure the tank is topped off so I can gravity bleed before I bleed the engine with the pump.