Example
Moving away from a skeleton, provoking an AoO, does the counter come before or after the attack roll?
most counters come after the attack roll, but before the result is revealed, if I recall (don't have it open in front of me).
I was just going off what's on the d20pfsrd so it didn't really specify when the counter takes place
Counters are immediate actions, so they occur right before the triggering action.
So I wouldn't wait and see what the opponent rolls, I'd just do the counter first regardless of whether the attack would've missed me
from page 31 Path of War:
"Counter: A counter is a fast, usually defensive maneuver that is used to prevent or respond to your opponent’s actions. A martial disciple who dodges just beyond an ogre’s reach is using a counter."
[cut some irrelevant text about iron tortoise using shields here.]
"Counters are immediate actions that you attempt during an enemy’s turn. Usually, your foe must make a specific action, such as an attack against you, for you to use a counter."
also, same page:
"CRITICAL HIT VS COUNTER
As this is bound to come up at the gaming table at least once in a while, a player or the DM will roll a natural 20 against a creature or player and the decision to use a counter will arise. Relax, here's the answer. Counters may be used against a critical hit except if the threatening attack roll was a natural 20. Critical hits from weapons with extended threat ranges (such as rapiers) can be countered if the threatening attack roll was not a 20."
that side bar is what makes me answer the way I do.