I've always been particular to pre-pending the current time (epoch, date, whatever) to the start of a UUID of some sort.

Mathematically, you're actually more likely to generate collisions this way, but we're talking 0.00001% in a million years vs 0.001% in a million years. It won't happen either way, practically speaking.

And the benefit? It's usually easier to explain to other people. It's more intuitively safe because there would need to be two colliding keys generated the same second.