The research about narrative memory, from what I recall,
suggests that we re-write our memories through the process of recall, with these early autobiographical memories forming their own stable storyline around the end of latency age (so 10-ish). Younger children appear to recall with less discrimination, whereas older children have formed go-to memories that mark moments in their early childhood.
In general, research on memory in young children is fraught with challenges. A discussion which, in my mind, always leads to the ritual-satanic-child-abuse-in-daycare cases in the 80s. (In case anyone is wondering, pretty much universally found to be products of very poor interviewing technique--and worse--in well-meaning child safety advocates.)
