Either a 4 or 5 days trip. Bad news is it seems like the accomodation at Laban Rata is highly sought after and theres only less than 2 months to go. Higher chance to get teh accomodation there if we go along with one of the packages offered such as that by
http://www.boac-online.com/
Good thing about 5 days is that you can have 2 nights at the Laban Rata resthouse and do not have to descend on the same day.