You can wait until Sunday to shock the pool but ..... if there does happen to be an algae bloom in the works due to your chlorine level dipping so low, your water won't be sanitized. Why don't you do this. Test early in the morning before the sun really gets on the pool. If you have lost more than 1ppm of chlorine overnight from where you are now, you will know that there is something going on with your water and you need to shock. You don't want kids swimming in water that is unsafe. If, there is not more than 1ppm loss overnight, then add enough bleach in the morning to take the chlorine back up to around 12 and let the kids swim. Take a look at the chart at the following link.

http://www.poolforum.com/pf2/faq.php...aq_bg_chlorine

Swimming in a pool with cya of 110 and cl of 15 is no more "dangerous" than swimming in a pool with a cya of 40 and cl of 6.