This sounds like a lot of headache for very little gain. Now you have two calendars to keep track of (because let's be real, this won't gain widespread adoption) that gives you less information than the Gregorian calendar.
Clocks count upwards precisely because time is infinite. When you count down, you're counting towards a finite point. The Gregorian calendar is already based on meaningful celestial events - a complete orbit around the sun and a complete earth rotation. And just like Maker Time, it resets every year.
Yes, you get this feeling of workable time periods, but we already get this with clocks. And with Maker Time, your periods are pre-defined: 12-8, 8-16, 8-24. if you work from 9-17 (like many people), Maker Time already encroaches upon two different periods.
Lastly, you can't realistically schedule anything, because an 8 hour window is too large to coordinate. It's a good attempt. I'm not just commenting to crap all over Maker Time, but it solves a non-problem.