transitioning from 2 naps to 1

Di

my son is 17 months and i’m trying to transition him to 1 nap. he loves his daytime sleep (sleeps 3 hours or more between both naps) but it’s been getting harder to get him to go to bed at night because he’s just not tired and then he’ll wake up really early the next day. anyway the last few days i’ve just allowed one nap, starting around late morning 11 am or so. Problem is he’s only been napping 1 to 1.5 hours and then is up until bedtime. By bedtime he’s cranky and overtired. I’m hoping he will gradually adjust and start taking a longer midday nap. 2 to 3 hours would be great. then go to bed by 830 and hopefully sleep until at least 7 am. fingers crossed 🤞🏼