safe sleep environment for a toddler

[Cheeseymondo]

We have used the lullaby trust sleeping bag tog rating and what a baby should wear for bed based on different temperatures and we’ve always kept his room at 21degrees since he was a baby. Now he is 19 months do these same principles still apply. Also when is best time to transition from sleeping bags to blanket/quilt? What age is best for transitioning from cot bed to toddler bed?

A duvet/blanket/quilt is fine at his age. The advice I’ve seen varies from 12-18 months but as your DS is 19 months he’ll be fine. Ikea make a great toddler duvet that’s very reasonable if you’re looking to buy one. If he’s too hot he’ll just kick it off. There’s no need to specifically keep his bedroom at 21 degrees overnight, unless you’re keeping the house at that temp in general (it would be too hot for me!)
In my opinion, move to a toddler bed when he’s making moves to escape the cot or if you’re potty training and he might need to get up to go.

21 sounds hot! I had no idea that was the guidance. We only have the thermostat that high when it's snowing. I'd be wary of losing the sleeping bags if they tolerate them. They can climb out of cots when they are out of sleeping bags. If you need to buy bigger, get ones with zips, they can be put on backwards once they start to try and escape. Personally I only move them to a bed once they are climbing out or potty trained.

I kept dd in the gro bag til the summer after she was 2, so she could kick it off if hot. we changed the cot bed into a bed around the same time.

Dd was in a sleeping bag until 21/2 I think.She would sleep in a bedduring the day for a nap but refused at night so she stayed in the bag while she was still in the cotton stop her climbing.
She moved into her bed once a Winnie the Pooh duvet appeared.She screamed the place down though when we tried to move the cot out,it had to be furtively removed piece by piece.