Four to seven months is the ages between which your baby will be able to sit. Your baby will have mastered rolling over and holding his head up. Most babies can sit well for several minutes without support by the time they’re 8 months old.
At the age of 4 months, your baby’s neck and head muscles strengthen rapidly, and he will learn to raise and hold his head up while he is lying on his stomach.
By 5 months he may be able to sit momentarily without assistance, though you should stay nearby to provide support.
On reaching age of 7 months he will be able to sit unsupported, and he will learn how to pivot to reach a desired object while sitting.
At this point he may even be able to get from his tummy into a sitting position by pushing up on his arms. By the time he is 8 months old, he will likely be sitting well without support.