Temperatures 38 and over, I wait 24 hours before taking them around other kids because they are still contagious. If it is just a low grade temp (37.9 and under without panadol) then as long as it comes back down, I am okay taking them out because low grade temps can be caused by teething and other non infectous things.

Clear snot and no other symptoms we go out but green snot or more than just a runny nose, we stay home and away from other people.

Anything gastro, we wait 24 hours until the last symptom (not just for the sake of others but it's not fun to clean up when we are out either).

I guess most of it depends how the kids are feeling as well. Symptoms are one thing, but if they are feeling miserable, it is not fair on them (or the people we are going to meet) if they aren't feeling well because they are cranky and out of sorts and don't enjoy it anyway.

Having said all that, while I don't take them to playgroup and the like while they are unwell, they don't cope with being cooped up for too long so often we will go to the park or for a short walk late in the afternoon just to get them out a bit which seems to help them get better sooner. We tend to steer away from playground equipment and stick to open spaces, but it does do wonders for helping them feel better.