The only thing I can think of about the third bud is at the top to let that be the growing tip.
I wouldn't worry about those measurements too much, the tree will dictate the spacing of the buds/new branches. You'll have to let it grow and figure out how you want them spaced.
Ahh!
Here's a quick video talking about your third bud, it's to let grow to make another tier.
https://youtu.be/1vvBHLltEZg?t=193