I think it is wrong to pin down a date because then you are establishing a hierarchy.
Tw suicide mention
If you were to ask the others when I was first on the scene they would tell you maybe 7 (my first attempt to kill us) but they would be wrong. I have memories from when we were in bursary being punished for being lefthanded. Noone else has those memories they are mine alone. So on that basis I have been around since we were 2 1/2 but I wouldn't claim that personally as I don't feel different from the others in those memories. if someone were to play my memories on a reel the earliest ones would be played by an actor who looked and sounded like the body the midsection I'd look like Mr tumnus or the creepy faun from pans Labyrinth more recent ones I'm just a guy with a goatee. By 7 I was and entirely different person I wasn't even the same species as the body but what about the time between 2 1/2 and 7 at what point did I stop becoming part of the whole.
Tw end
There are 4 of us who can trace our earliest memories to before the birth of our first sibling (so younger than 3 1/2) all 4 of us I believe were always present. Life prevented us from fusing something happened and we solidified as seperate people. All 4 of us have the ability to splinter, our protector splintered from one of the others when they were powerless to stop me, we don't know which, does it even matter? Our mother figure splintered from one of the littles to balance the protector (who is a bit of a loose cannon), we don't know which we don't know when, does it matter? Lord knows where the caretaker comes from. Does it matter? One of our newly concious alters who is only just learning to front developed from a fragment of grief that was created when we were 2. So did she "become" back then or does she only count as existing from them moment she became self conscious.
Acordind to the Triad of dissociation an alter developes from the constant dissociation of similar memory types into the same neuron pool. It happens in 3 stages 1: total or partial memory is hived off behind an anmesica
wall - observable symptoms look like dp/dr/spotty memory
2: memories behind amnesia wall layer up sufficiently to make connections which become triggers for activation, level of influence on body depends on other information available to the memory pool detailed memory pools start forming conciousness some pools may have a single function available to them eg.running. those capable of being interviewed during therapy will display the same level of self awareness as a preschool child capable of understanding they are seperate from their playmates but incapable of identifying which of their likes are their opinion or things that they do because they mimic the culture they are raised in- observable symptoms may look like BPD/osdd/dissociative fuge
3. Memory pools now have at minimum similar number of connections to the memory bank of a young child (traceable through various psycho analytical methods) they are capable of concious thought, formulating opinion based on past experience, reacting to their surroundings, actual mental age of these developed personalities varies. - observable symptoms osdd / did
At what point in this Triad does an alter count as having split? Not all stage 1 pools go on to becoming alters but all alters start at stage 1.