There are so many posts about this so I figured I'd add our story in case it helps anyone!

DD was 14.5 months when we went down to 1 nap. And her sign was not fighting either naps; though both naps were getting a bit shorter than usual. The big sign for us was actually her fighting bed time. Her 2nd nap wouldn't end till 4-4:30 and she'd be up till 9-9:30 and still fight bed time.

So we bit the bullet and just moved her to 1 nap. She would literally pass out sitting there by 11am, and the first ~2 weeks were hard; her naps weren't getting that much longer so there were day she was up by 12-12:30 and she'd be out like a light by 7pm.

Now at 15 mo we're happy to say that 1 nap is going really well! Some days at home she'd nap for almost 3 hours! And she def is asleep by 8. She is able to stay up for 7 hrs between nap and bedtime.