2lumpy, virtually all Kilimanjaro climbs are guided. My daughter and her fiancé climbed Kili in late February. They summited on their 6th day. It was a private climb, as in no other tourist climbers in their group, but the support staff which consisted of guide, cook, porters, etc. consisted of about 20 people. Typically, people climb in groups and most plan on 7-9 days to get to the Uhuru Peak summit.
Acclimating is extremely important. Both my daughter and her fiancé are very fit distance runners, my daughter runs marathons and he runs ultras up to 100 mile races, and they were fine with no AMS symptoms up till around 18,000 feet. He was fine at the summit but my daughter got fairly sick the last 1,000 feet of altitude gain. The watched the sun come up, then she ran down to lower elevation, puking twice on her way back down to 16,000 where they’d camped.