I agree with the observation that "early" isn't everything, and I'm not sure that it's truly meaningful if milestones are more-or-less on time. I think it's a lot more about atypical development (skipping or inverting milestones) and really astonishing acceleration (you know, the kind where you rationalize away what seems impossible by any means possible).
One strikingly illustrative example of 'early isn't indicative' is a comparison with a nearly perfectly matched child my DD's age (literally-- B-days same week, both with two-PhD parents, both only children, similar in appearance). Both girls were highly verbal and played well together (not parallel) at age 2, when they were in daycare together. If anything, her vocabulary far outstripped DD's. They were apart for several years (academic nomadism) and next met when they were about six. It was shocking how... ordinary (?) this other child seemed by comparison to my DD. My DH also remarked on it, and he's not one to do that. His question was; "Huh. What happened??" I mean, she was still the same lovely child, but she seemed comparatively so--so-- placid and incurious. It was as though her development had plateaued, whereas DD's had taken off exponentially. So her verbal precosity wasn't really significant, though at 2, it would have led to speculation that both were MG+, and the other girl likely PG. We know them still; the difference is staggering now that both girls are adolescents. The other child is a pretty typical middle schooler, and DD is, well-- not, and I can't even imagine it. So no, 'early' isn't 'gifted' necessarily.
It's not about the snapshots, it's about the trajectory.
It's that velcro-brain and avid/obsessive interest in the world at large that comes to mind when I think about DD being so very different. Many of her early daycare carers were quietly agog, but we figured that they probably were 'flattering' to most children, and didn't think that much of it.
Some of the most striking things about her earliest development was that she had a keen sense of self at a very young age. She was also just so weirdly observant of everything ALL.THE.TIME, and eerily empathetic and socially astute (this was the thing that inspired AWE in carers, to the point that a few of them recall her VERY well even over a decade later). She seemed to understand that other children (<2yo) didn't have the communication skills or cognitive awareness to exert self-control or experience true empathy, so it was as though she needed to compensate for any other peer she was engaged with. She shrugged off antisocial behavior in peers (though she had her own ways of casually, passively resisting being run over by them-- and she did this with grace and seemingly no effort at all). Eerily 'knowing,' really.
One more early thing that was downright bizarre. When my DD was not quite two, a new infant (just 12mo) entered her daycare. His home was Spanish-speaking, and none of the adults at the daycare were bilingual. He was a very sensitive little boy-- who was highly distressed, and cried and cried his first weeks in the new setting. One of the carers told me his background in passing on the first morning; apparently DD understood that or at least worked it out from what she'd overheard.
DD was obviously very concerned about his obvious distress, and gravitated toward him. The next day, she wanted to learn "some Spanish." I thought this was innocent enough and taught her how to say hello. A day later, she wanted to know what else I knew. Why? She needed to "learn real Spanish." Why? This other child just didn't know any English and she wanted to help him. Oh, and that it made the caregivers and other children less tense, too, because he wasn't crying all the time now that she talked to him in Spanish. She needed to know more than "Hola" and how to count to ten. When I wondered where she had learned the numbers, the answer was a casual "Oh, Sesame Street yesterday afternoon because Rosita speaks Spanish sometimes."
"I need to know more, mama. I can't just count and say hello to him all day long. He's going to know that I can't understand what he says back. Besides, 'hola. hola. hola.' It's silly."
The initial foray was evidently an experiment to determine if the child's distress was solely because of the language barrier. She was quite concerned that this was her responsibility since nobody else was stepping up to the plate.
There were a handful of those unsettling moments with DD as a baby, toddler, and preschooler-- most of them didn't really register as unusual for her, so some of them I haven't really thought about in years and I certainly didn't annotate them anywhere at the time. Looking back on them, I'm amazed.
