I only had 2 metres of fabric to work with and I'd chosen a blue and white stripe...so no chance of fudging it.
I then cut the square gussets from the offcuts. Which were inserted the same way as you do with a chemise/shift. Before I sewd the sides. Then I pressed the side box pleats and sewed them in place.
DISCLAIMER - This was me making it up as I didn't understand the instructions.