[Marshall57]

When removing the oil pan, you will lose the oil that is usually stays in the dip tray. After start up the oil pump will have to pump enough oil to fill it and get it flowing to the other parts of the engine. To get the oil moving to the right places sooner it might be a good idea to remove the distributor and pour about a quart down the distributor hole to fill the dip tray before starting the engine.
On a new engine this is essential but on an engine that has had a good oiling just before the oil pan was dropped, it might be just a good idea and cheap insurance.
Also take care to use exactly 5 quarts and after it has run just a bit check the oil taking note of where it is on your particular dip stick. There have been cases where even though there is the required 5 quarts in the oil pan, the dip stick reads low. This has led to a problem of trying to keep the car over full and the car reacting by promptly tossing out the extra oil and the owner then refilling thinking it is low. This misery is easily avoided if you are at the point of putting oil in an empty oil pan.
Later when changing oil, not all of the 5 quarts will come out due to the dip pan holding some oil so adding five quarts will over fill it just a bit and the engine may toss it out, knowing were the proper level is will help later.