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, SEARCHING FOR A NEW MAIN STRING / Hexy Fiber 16 @48/53, dropweight stringer