Joining a group on mt Kilimanjaro is normally done during the high season.
All routes are possible to find a group to join.
January and February are popular months. July thru September are also the dry season and are "high" season. April to mid June tend to be the rainy season. Many people will combine a photo safari before or after the climb, so I would recommend going during the dry season.
Thousands of travelers come to Tanzania each year looking to join a group on safari or a climb up Mt. Kilimanjaro. These travelers - usually backpackers - are looking to save some money and join a fun group for their adventures. The theory is, the more people you have on a climb or on safari, the lower the price.
In fact, it's almost too expensive to go on safari alone (Kilimanjaro can be managed), as the cost could start at about $198 per day per person for a very, very budget trip - that's if you are lucky and anyone is willing to take you.
Another advantage of joining a group especially on climbing mount Kilimanjaro, is that you get more courage, and share history of other climbers.
Example if you take 6 days trip you get 198 $ x 6 days= 1188 US $ per person.
All services are included in this package.