Well, here are some exceedingly general trends, at least for the U-S:

1. Transatlantic flights typically arrive from Europe in the mid-afternoon.

2. Flights to beach destinations (Mexico, Caribbean) typically depart from the US in the morning and return late afternoon. This adds to the busyness in airports that have a lot of Europe flights.

3. Inbound flights from South America typically arrive first thing in the morning. So the relative handful of airports that have these flights can be very busy in the 5-8 a.m. range.

4. Flights from Asia are all over the map in terms of arrivals.

Conclusion: Try to arrive at customs between 9 p.m. and 4 a.m., or at roughly 10:25 in the morning.