If you know pixel-element background doping then you can get
lifetime. It's statistics from there on out, just how long a loose
carrier-pair will survive.
If you're trying to count single photons then you probably are
not that worried about high arrival rate. Or, it's a statistical rarity
that you might be prepared to tolerate by the time you get to
high "counts per frame" or whatever.
Because time-of-arrival is random, you can't "ensure" anything.
Just figure out how to spec and how to deal.