A bunch of fresh 90s with no prior raiding experience can probably clear up to at least Garalon in 3 days, as long as you're reasonably competent at the game and intelligent about preparing for the fights and adapting to them. Garalon is kind of a gearcheck (less so now than prior to the enrage nerf but still pretty harsh), which would be a problem. Garalon, and the next three fights in HoF, are all fairly difficult, and I dubt you'd be able to kill them in just 3 days without any normal mode gear farming or prior raiding experience this tier, unless you're very much more competent than the average raider.
You could probably skip those 4 and, if somebody opened terrace for you, clear terrace, which is a much easier instance than the final half of HoF is.