Here are the approximate measurements of what I cut, but because of the stretch of the fabric I think that you have some wiggle room. My daughter is a 4T so that is the size of the measurements below. It's maybe a little tight too so keep that in mind when you decide what measurements to cut.
Front (cut one of knit and one of lace) :
Back (cut one of knit) :
Sleeves (cut two of knit) :
Waistband :
3 inches tall (folded in half to 1 1/2") and 23" long
Neckband :
2 inches tall (folded in half to 1 inch) and 14" long
First, sew the lace on top of the front piece by either edge stitching or serging the edges. Then with right sides together, sew or serge the sleeves to the front and back as shown. (I am using a serger so everything is at 1/4" seam allowance)
Match up side seams of shirt and sleeves with right sides together. Stitch from sleeve end to hem.
Create waistband by sewing it into a circle, then folding in half lengthwise, pressing and stitching closed. (I didn't have enough fabric so the inside half of mine is another knit fabric)
With right sides together, sew the waistband to the hem of the shirt, stretching the waistband slightly as you go so that it fits the circumference of the shirt.
Repeat for the neckband and you are done!