All members must be present on the first day of our scheduled itinerary in Kathmandu unless you have made special arrangements. We need your passports on that day so that we can obtain the permit for you to go to the mountains, and do quite a bit of intensive orientation and training before setting off for the mountains, in the next day or two. Of course it is fine if you wish to arrive earlier than the first day of our scheduled itinerary.
In addition, we need you to stay until the last day of the expedition unless you have made special arrangements. Its OK if you want to leave a bit earlier, but schedule your flight for the final day in any case. You never know when bad weather or route conditions can slow you down and cause you to need each and every day. Of course its fine if you want to stay on after the expedition ends.