Can't help much here. Mine sons were all 4yrs old. There's an age old expression,"they won't start kindergarten in diapers." means, by that age they'll be developmentally there. Preschool allowed pull ups for the 2 of mine that started as an early intervention. One son was 4.5. One just magically fell into it on his 4th birthday.

The pressure is stressful. Fingers crossed for 'you'!