If your hub has the correct spacing to be used then the wheel should be centralised over the spacing, whether front or rear. European wheels were always built with the inside spokes going in opposite directions. I always found this easier than having them face the same way, another americanism.
The spoke holes in some rims are angled as well as staggered.
Some hubs have alternate spoke hole countersinks, these are to support the bend in the spokes.
If you want to look like a professional wheel builder have your spokes in the same direction and pick up 8 between thumb and forefinger 3 or 4 inches from the thread and fan them out using the second finger. Makes it easy to drop them through the hub if the rolled thread has enough clearance.
I have mentoined before I sometimes bought spokes in excess of 100 gross lots for my little 1 man shop.