Take one piece of the Waistband, cut the pocket opening notches at the inside LHS side seam, fold back and stitch the pocket opening edge. Take the pocket bag and align with the side seam opening, topstitch around the curve.
With right sides together join the side seams of the both waistbands, take care that the pocket opening is not caught in the side seam. Topstitch if desired towards CF. You will have 2 pieces, inside and outside.
Check the finished waistband measurement and cut elastic to your personal length. Overlap the ends of the elastic 2.5cm (1”) and stitch closed. Your elastic loop will now be 2.5cm (1”) smaller than the finished waistband. Sew the edge of the elastic to the top edge inside edge of the of the inner waistband.
With right sides of the 2 waistbands together join the waist edge to the elastic. Stretch gently while sewing to ease the fabric to the elastic.
Turn out the waistband to the right side and topstitch the elastic 6mm (¼”) from the seam on one side. This will be the inside.
With right sides together join the CF crotch seam. Topstitch to one side if desired.
The gusset will be double layered. Place the 2 gusset panels together and treat as one piece, then with right sides together sew one side of the gussets to the back crotch, fold and topstitch towards the side seam.
With right sides together sew the 2 CB crotch seams together finishing at the other side of the gusset. Fold and topstitch (if desired) towards the side seam.
With right sides together attach the back yoke to the main back panels. Match the CB pant seam to the CB yoke notch. Fold towards the hem and topstitch.
With right sides together join the front and back inleg seam. Start at one leg opening, match notches and finish at the other leg opening. Note the CF crotch seam will be in the centre of the gusset. Fold and topstitch towards the front.
If making the side splits, overlock/serge the split edges.
With right sides together join the side seams. If making the side split, sew to the top of the splits where noted on the pattern, otherwise continue straight down to hem.
Fold and topstitch around the outer edges of the splits.
Fold the waistband over so the elastic is inside, and with the 2 edges together join to the right side of the main body. Match at side seams and CF/CB. Stretch slightly to ease the main body to the band. Fold and topstitch downwards.
Fold and press the hem, stitch with twin needle, coverstitch, or zig zag.
Give the garment a final press and finish.