Transition to 1 nap or not?

[ItsNiceItsDifferentItsUnusual]

Ds2 is 12 months. Until last week he had a great routine:

Up at 5.30 (annoying but able to live with it)
Nap 9-10.30/11
Nap 1.30/2 until 3ish
Bed 7pm

He did really well on a strict 3 hour wake time between naps.

Then last week we had some work done on the house which interfered with naps and we haven't been able to go back to where we were - he was refusing the second nap until later which then impacted on bedtime.

Due to his age I thought it might be time to transition to one nap. When ds1 first did his he slept 10-12 with bedtime at 6.30, and this gradually got later until he was doing 12-2 by the time he was 18 months.

Well at hell has broken loose with morning wake ups since trying this. It was 4.20am today.

Where am I going wrong? The early wake ups means trying to do one nap is really pushing him, but then two naps pushes bedtime later but the morning wake up is the same, so he's starting the day very tired again.

Any advice?

Could this be unrelated to those works - for example coincidental teething? DS got four teeth around that age and initially I didn't realise it was happening. Have you tried giving a little calpol before bed to see if it makes any difference?