> A problematic thing is they way ports generally work, you may generally not book a port for a specific arrival date. You have to rush to get there before other ships, to sit still outside and wait in line.

For most ports in North Europe that's not the case (though it used to be). You generally agree on a standard arrival date (day of week + time + number of moves), then you should arrive at that time. This differs per region though. For Africa, it's "different". You have terminals owned by customers, etc. More often you still have to rush, then wait for ages.

Maybe things are different if you're a small shipping line and the same terminal also working for a few big ones.