If the principal has the means of brooding the chick at her house -- or taking it to your house for you to do so -- that would be perfect. If not, the chick will likely survive a couple of days in the incubator, and that may be a safer solution than putting her unattended in a brooder for a couple of days. My main concern with leaving her unattended in a brooder is if there is a problem with the heat source -- either being too hot, or too cold, or failing altogether.