How far in advance to I need to book the safari?

For gorilla trekking trips, because gorilla permits get sold up to 2 years in advance and get sold on first come first served basis, we suggest booking well in advance.  
For Tanzania and Kenya Safaris, there is no cutoff. However, flights into Kenya and Tanzania are limited and we find that there can be problems getting seats on airlines if you try to schedule less than two months ahead of time. Peak seasons also book up as far as nine months ahead of time. Securing accommodation also becomes a problem as most lodges get booked up.  Mid to late December is a busy time in both Kenya and Tanzania. Outside of peak seasons, you should have no trouble booking if you schedule your safari at least six to eight months in advance.