So chicken pox is contagious before the breakout and while the blisters are open. Your family may have already been exposed. It takes about 14 days from initial exposure to when the break out occurs. I dont know if your SD can bring it home or not, but I would def steer clear of the school for a while with your babe even if they have possibly already been exposed. I would call your DR tomorrow and get the oppinion about the vaccine.