It is still knit from the bottom up, but it would easily be knit from the top down if you wanted to
not run out of yarn. Just follow the pattern backwards. The only difference is that instead of decreasing on every bodice stitch you would increase on every stitch by kf&b or M1. The kf&b would add in a purl look stitch every second stitch. the m1 would add an eyelet look after every stitch.
ALTERATIONS - for bottom up - In the round 0-3m (6-12m)
CO 112 (136)stitches. Follow original pattern from here.
After the decrease for 'puff' in bodice. split the stitches 50/50 for front and back. Continue on original pattern.
When sewing ends in i like to strengthen the split for the bodice with a 3-4 loop stitches. This stops any pull / stress on the garment when being put on the baby and also looks tidier.