Transitioning from three naps to two !!!! (Will be 7 months on June 6th)

So last two days, my baby is refusing the last cat nap!!!! He woke from second nap at 1:40 pm..... I know any bedtime before 6:30 pm is wayyy tooo early , so I’m planning and keeping him awake.. until 6:30 and that’s five hourssssss, which is a longggg wake time compared to what he’s used toooo.... I fear an over tired baby ! So. If he starts to yawn at 5:30 pm , put him to sleep? Even if it’s early ???? Or keep him awake and ignore the yawns and put him to bed at a later time, like 6:30pm

Help!!!! How on earth does a Six month old baby take two naps without being over tired?????? I know every baby is different, jus not sure what I’m supposed to do lol