My son is 28 month old 28 pound and almost three feet . when is the right time to transition him to bed . he does not seems comfortable in crib anymor?

Fine: The transition to a bed is more a safety issue than a timeline. If the kid can stand up and attempt to crawl out, it is past time to get him to a lower position closer to the floor. You can put the baby mattress on the floor against the wall to soften the change.There are roll bars you can by or make to prevent his rolling off the mattress.

When he climbs out!: There are no rules about when to transition from a crib to a bed except safety considerations. When toddlers find they can climb out of a crib, then they are at high risk of falling and getting hurt, so a toddler bed which is just off the floor is ideal or a regular bed with a rail is an alternative. Getting your child to stay in bed at bedtime and during the night will be a new challenge.