We only transitioned DD out of her bags as she was going into a bed and I was worried she would try to walk in one without much success! She was only a couple of weeks shy of her second birthday.

With sleeps bags I felt so confident she was nice and warm all night as she's a real wriggler, now in a bed she wriggles out from under the covers so we have to dress her warmly, although it has only just started cooling down here.

Perhaps keep her in bags until after winter so you know she's nice and warm at night? We couldn't transition out of bags whilst DD was still in the cot because then she could throw her leg over and climb out!