Technically it is supposed to be 48hours from last spew but I am sure there are plenty of parents that don't wait that long. I am lucky that DS (touch wood) has never had gastro and has only ever spewed twice in his 2 short years. He has been at daycare since 6 months old.

He gets more than his fair share of colds and coughs though and we just alternate who has to stay home until he is at a stage where if he was someone elses kid I wouldn't be annoyed if I saw him at daycare.