Sorcerers are arcane spellcasters who manipulate magic energy with imagination and talent rather than studious discipline. They have no books, no mentors, no theories—just raw power that they direct at will. Sorcerers know fewer spells than Wizards do and acquire them more slowly, but they can cast individual spells more often and have no need to prepare their incantations ahead of time. Also unlike wizards, sorcerers cannot specialize in a school of magic. Since sorcerers gain their powers without undergoing the years of rigorous study that wizards go through, they have more time to learn fighting skills and are proficient with simple weapons. A sorcerer can call a familiar: a small, magical, animal companion that serves her. Charisma is very important for sorcerers; the higher their value in this ability, the higher the spell level they can cast.
I would argue that since sorcerers abilities are based off an innate talent rather than studying they would have said abilities at level 0 depending on the player's interpretation.
This is reflected in approved character submissions, such as the case in Annabelle Switch's approval:
Annabelle grew up the daughter of Kheldell farmers, she lived a typical life for her first 15 years until one day when she accidentally cast her first cantrip and learned that she had a natural affinity for the Al'Noth. a year later she was practicing with when she accidentally started a fire in her Kheldell home
Here the character discovered her talent at age 15, what I would argue is level 0 (because approval for level one requires the character to meet the minimum age requirement for that race).
The submission of Samnyma suggests a similar interpretation:
She [the woman, Magra] had recognized Samnyma's gift for sorcery from an early age in the child's life. It seemed that some of the many events that twisted her childhood were not entirely happenstance.
I read your submission, and I do find it interesting. It seems almost like the master cleaned up a 'rogue' figure except in this case the urchin-like tendency is magic. If the master, taught, or beat the character into not pursuing his innate talent even before he was of minimum age it doesn't seem necessary to take a level in Sorcerer.
Your words "blossom" "manifest" and "mature" are quite different as well. Blossoming and maturation are a kind of coming into one's own, a show of development, whereas manifestation is just a kind of presence. A "raw power" may exist within him, but if it is so blocked by his discipline as though it does not exist, then I don't see why taking a level in sorcerer is necessary.
In short, it seems to me, from the Lore and approved character submissions, that a sorcerer's ability preexists level 1, but that it is not necessarily controllable (in Annabelle's case it seems more manageable until the fire, and in Samnyma's it seems to influence events in a way Samnyma is unaware until later). Regardless, there is something manifested before level 1.
What may be interesting to think about, on top of the self-loathing quality of a path the character
might have gone down would be what if at some point later in his life he faced a challenge that might even require him to tap into that innate ability? What if at some point he became so wholly defeated there was a doubt in discipline? That would be an interesting character development, too, I think.
I digress, though, I am merely speculating off my research. I am nowhere near qualified to give advice on the matter.