Jeff IMO shoot the stage whichever way you are comfortable with. The breakdown of what you are talking about depends on what division you are shooting and the plan you have for shooting the targets downrange.
The first array you are talking about though had 2 basic ways to shoot it. Open door first or after engaging the 3 targets and moving forward like you did.
First plan start at front and open door while stepping back the 6 feet or so to see the other three targets.
Advantages-
Can open door while stepping back.
Drawing gun while stepping back to a position to shoot the other 3 targets.
Can engage all 4 targets from 1 position
Once shooting you don't have break your grip between targets.(to open door)
Disadvantage
Have to back up while drawing(slightly slower than moving forward)
Longer shots on the headshot (6 feet or so)
Starting at the back Advantages:
Closer head shot
Slightly faster moving forward
Disadvantages:
Have to break the grip on the gun to open the door
2 shooting positions
Danger of sweeping your hand when opening door
A rule of thumb is approximately 3 seconds for every time you add a shooting position. It take about that amount of time to stop and align the sights and shoot 2 shots and get back to speed moving.
Both starts above have to cover the same distance forward or backward. Both have to open the door although the shooter that starts in the front can open it while moving backwards.
Only have to start and stop 1 time when starting at the front.
Again if you are not comfortable backing up or it doesn't feel right do it how you need to.
Starting at the front was probably 2-3 seconds faster for me.
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