The red band is the obvious vertical - your centre back should be the point between the two sets of three white lines. It really can't be anywhere else without making the kilt look lopsided.

When pleating to the sett the whole idea is to recreate perfectly the pattern in the pleated section, and you would usually have a strong vertical band either centre back or have two equidistant from the centre back. You would also try to have the same situation on the front.

The sides are not as important - fudge them as best you can without compromising the placing of the red verticals. The ideal is to have a whole number of repeats around the kilt, so the edges of the pleated section are not really obvious.

The amount of fabric on each side will be the same even if you have apparently one less pleat on the right, as there is an approximately double width pleat as the last pleat - I wonder if the reason there is a larger pleat there is because the same thing happens regularly when pleating to the sett and it just evens things up?

Hmm - lightbulb going on moment?

You then have the two under apron pleats and the aprons and have the same amount of material on both sides of the centre back.