When do you stop using an infant insert? I am using the ergo infant insert

According to the Ergo website, their Infant Inserts are designed for a parent to safely carry the newborn baby from day one (if they are 7lbs or more) until age 4-6 months. It is designed to provide ultimate comfort and support for baby, by providing head, neck and spine support and ensuring baby is correctly seated while in the Ergobaby Carrier. They recommend that once your baby is able to hold her/his head up for long periods of time and is comfortable with her/his hips in a splayed position, the use of the Infant Insert is no longer necessary. For more information: http://store.ergobaby.com/ergobaby-faq#sthash.TkpRJ09L.dpuf