Preemie baby growth spurt

Frances • Momma to E and furbaby Ace. Pregnant with baby #2!

I know they say there are certain ages when babies hit growth spurts (3 weeks, 6 weeks, etc.) but with preemies do they usually have these spurts at their actual age or adjusted? Just wondering as sometimes I can't figure out why, I would assume growth spurt except it doesn't generally coincide with the typical age for him. My son was born 6 weeks early. Turning 5 months actual on Wednesday.