My son wil be going in 1st grade from April 2018.His age would be 5yrs 4 mths.I have come to know child should be atleast 6yrs of age when going to 1st grade.Should i repeat him in kg and wait for another yr when he wil be 6 yrs 4 mths.Tht way he would be more mature in grasping things...Plz advise