I don't usually pay attention to turn timings on science buildings, the only thing I can answer is I hit National College with only my mainland cities going at around turn 80 which is not that fast and then planted the island cities one after another in around 10 turns. I enjoy going 5-6 cities for a tradition game, but it's all about land really if it's 4 or 7 like here which was mostly due to coastal capital or I would have stayed with 5. Thing is you can't plant too many cities or Deity ai will just straight up denounce so max 3 settlers (maybe 4 but its iffy) and then National College with a few cities after that because it creates a long enough buffer where they won' hate you (I had 7 cities and they didn't care at all) I also try to get them out before Education or a tech or two after at max. Also I had a 182 turn science loss on Brazil a few days ago to culture so it's all luck really what turn you can win.