My Ho Yin could turnover one side from 4.5 months.
However, he wasnt interested in turning at all.
When he was 6 months, he could turnover both sides and then he was more interested.
He is turning all the time now.
Different bbs have different stages!!!
Let them take their time!!!
No hurry!!!
My son starts to roll over by himself when he is 4.5 months old. Every baby's development is a bit different. One might be early in reaching one milestone while lagging behind on other milestones. So don't worry too much over it as long as the Dr. said the baby is up to par during regular healthy baby checkups.