It won't be a lot. You have to consider driving home after taking him to school, and then leaving to get him. For a 2.5 hour school day, I get maybe 2 hours of time. For me, DD is in afternoon preschool this year and DS2 still naps, so I am hopeful for an hour at least of time to myself. When DS1 started PM preschool, DD gave up naps and DS2 was an infant.