The way I remember the NES invasion at my house: none of the kids of that era even knew what a game console was. As far as they were concerned, this concept didn't exist, so it was Nickelodeon and soccer practice every day after school. I was managing a record store at the time and we bought used products from consumers needing cash. Some of the hustlers bringing stuff in regularly started showing up with not only NES games, but the units themselves. We kept hearing talk about some Mike Tyson boxing game, but that was all we knew. After picking one up, it was a pretty cool quick way for some instant gaming fun, so we hawked up every game we could find (there was a time when I almost had every US NES cart!) After a few weeks, I showed my nephews, who were hooked from the moment they walked into my room. Super Mario Brothers was a brilliant game, so that didn't hurt. Rad Racer used the same model as older console racing games, but it was NES, so count that in. And The Legend of Zelda, etc. In the very beginning, any game for the NES was considered worth owning simply because it was for the NES. Word on the schoolyards spread like wildfire as kids everywhere were dashing out to department stores to get their own.
At least that's how it went in my neighborhood. One day, nobody had ever heard of this thing, but in about a month's time, every kid in America had one.