It’s basically impossible to quantify generational beginnings/ends without some instantaneous cultural shift. The best we have nowadays compared to the Baby Boom is probably pre & post-9/11 and pre & post-Covid, with some separation for the rise of the Internet in a broader sense, but even they don’t fully capture the cultural changes. Culture tends to slowly replace itself, making being a “90s kid” born in say 1993 irrelevant because a lot of earlier Zoomers will know like 80% of the same cultural milestones such as TV shows, video games, etc, if not through lived experiences than through cultural mitosis.
To me, generations are best defined not like epochs (that is, with concrete starts and ends) but as a gradiation. For instance, saying “objectively” Gen Y ends ~1995 and Zoomers start there is dumb. It makes more sense, to me, to have a 5yr or so buffer. So pre-1995? Millenials. 1995-2000? Gen YZ, somewhere in the middle. 2000-2015? Zoomers. It’s all still arbitrary bullshit, but it’s arbitrary bullshit that soothes my ‘tisms more than the typical models do. One could get really fine-toothed and basically attribute percentages to each years of how “Zoomer” vs “Millennial” one is by year, but that’s arbitrary modeling for another day.