I wonder how long I can sleep

This is our last day of school before break!  Andrew has to work tomorrow, but only for a training that should be about an hour long...all of his grades are complete!  Robert has a doctor appointment and Andrew has agreed to take him.  They should be home by 5:30 and then I am wondering how late I have to stay up...can I be in bed by 10:00 tonight?  While Andrew has to be at work by 9, I am not responsible for anyone having to be anywhere until tomorrow evening...so I am wondering how many blissfully wonderful hours my body will allow me to sleep!!!