Funnily enough I've often thought about this. I came to the show relatively late (season 5 was almost over when I started watching the episodes in order from season one onwards) and I've often felt that I missed out on a lot. I've spent the last few years catching up on the fan-made stuff: artwork, episode reviews, reaction videos and show discussions on Youtube and, especially, the brony-made music, which has been a real revelation to me and the fan-related thing that I like best about this show.
I've occasionally wondered what it would have been like if I'd become a fan in the first season and experienced the fan phenomena of the time and sometimes I get a tinge of regret that I wasn't here then. They seem like they were interesting times and that I missed out. But really the show is bigger than the fandom, and ultimately I'm glad I got into it when I did and got to watch those first five seasons and the first three Equestria Girls movies at my own pace.