Funny story about the pattern - I got it free from a great yarn store in the north suburbs of Chicago, but it was only 1 page and seemed to leave some critical instructions out for a beginner. After much :doh: and I had to re-write it (it’s now 4 pages because I typed it out row by row). After having done this, I highly recommend knitting it in the round up to the armholes since front and back are knit the same.
The pattern gives instructions for size 3, 5, and 7. To make it for an 8 year old, you would likely just have to extend the length a little and use the guage to determine how many stitches to add for making the bodice a bit wider if needed.
For anyone that wants my “extended” version of the pattern, PM me your contact email address and I’ll be happy to email you a .pdf file of it for now until I can figure how to post it more publicly.
FYI - the yarn I used is what was called for in the pattern - Tahki Cotton Classic in Lilac #3928. It took me 4 skeins.