Even if you plan on having 30 pleats in your kilt it will not use up all 8 yards so my suggestion is the find the center of the fabric and start marking for your pleats outward from there. 15 in each direction. Then add the amount for your deep and reverse pleats, then the aprons, them the facings.

Cut off the excess.

BTW 30 pleats will mean each pleat is .766 wide at the hip and .666 at the waist.

Plunking those numbers into the formula from above means you need:

38" for the outer apron, its facings, and the deep pleat +
183.75" for the pleats +
42" for the inner apron, its facings, and the reverse pleat =
263.75" or 7.32 yards.