Yet another carbing question

Brand new to kegging but here's what I did: I took my triple hopped ale (primary for 3 weeks), it turned out only 4 and a quarter gallons, cold crashed for 24 hrs then racked into a corny and put at 30 psi and plan on leaving it for 24 to 36 hours at that level. Then vent and bring to 12 psi... SINCE it is just over 4 gallons should I just leave it at 30 psi for 24 hours? Or will the difference matter?
I am following BierMunchers advice from this thread

BierMuncher
All my kegs age now for at least 2 weeks at room temp...following a three week stay in the fermenter/secondary. Then it's into the chiller and onto the gas at 30PSI for 48 hours. Kill gas. Bleed. Drop PSI to 10 and serve. (I'll drop that to 36 hours if the keg is already cold when I hook it up.

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p.s. I ordered more corny kegs!

That's fine, but you might want to check it at 24 hours (instead of waiting the 36) just to ensure it doesn't get overcarbed.