Julia,
You and I are quite similiar. I have 5 children....ages 8,6,4,2.5,1. I have also hired someone 2x's a week in the AM so I get uninterrupted time with my older 2.
Once I set the "schedule" and posted it and adhered to it for a couple of weeks, life seemed to change. For us, getting up and starting right away was the route to go. Kids get up and are in the classroom by 8 am for morning prayer to start the day.
At the risk of sounding too rigid, we needed to implement something so that they had some ownership and responsibility in their day and what they were responsible for.
Most work get accomplished for us by lunchtime. I try and spend some time in the afternoon with my Pre-K-ers ( 4 year old especially) on "school work."
It will come together!