I'd set the grommets in first:
Use a cheap string at kind of high on the tension range.
Hit hard against a wall or backboard for a half hour.
Cut out the cheap string.
#1 above, taking your best guess for the new tensions.
Dunlop MuscleWeave 200G 95, Bosworth/Lendl hybrid pattern - Black Out 1.24 / Hexy Fiber 1.26 @53/53 Alpha Pioneer DC+ dropweight