I'm not too sure if it makes a big difference. I know this subject has been beaten to death on this site
before with people doing it both ways.
I only lower the stabs before raising the roof cause the dealer stressed that point to me, said it helps for the roof to go up evenly, and it is in my owner's manual, laterally on page 49.
Dealer, Roberts Sales in Denver, rents popups and also gave me a nice laminated instruction sheet, that they give to renters, and that info is on this page.
Flagstaff Camping Trailer Set Up Instructions | Roberts Sales - Denver, Colorado