Nairobi is 6.5 hours behind Adelaide
Best overlap: 2:30 PM to 6:30 PM in Adelaide is 8:00 AM to 12:00 PM in Nairobi.
Book within 2:30 PM to 6:30 PM Adelaide time (8:00 AM to 12:00 PM in Nairobi) and both teams will be at work. A 4-hour overlap gives you a workable daily window; aim for earlier in it to avoid clipping the end of someone's day. For part of the year the maths changes: Adelaide observes daylight saving, Nairobi does not, shifting the overlap by an hour.