If the targets aren't taken out, then the follow on consequences don't come into play. As the total strength of the poison attack is your fists rating, high endurance and a bit of toughness are going to make the Poisoned state mostly irrelevant. If you can strike and disengage without substantial resource expenditure and without time pressure, whats stopping you from just taking them out in the first place (possibly one at a time)?
As for 'when' the monsters shrug it off (assuming they aren't taken out), they shrug it off at the point where the make a maneuver roll sufficient to remove the Poisoned aspect. If you are lucky, they will spend a consequence to help make the roll, but as you've disengaged, the only thing they have to worry about is the poison itself, so, to some extent, they are at their leisure to maneuver to provide enough tags to remove it (be those endurance maneuvers, magic, survival, etc).