I’m a newbie, but I think this @codinghorror post would help you to understand more about the Phases.
Once said that, I wanted to avoid more than 3 plots on Phase 1 & Phase 2. My time for P1&P2 with three plots was around 4h per plot (used plotman to check), so I guessed staggering them by 2h would work (and it does).
In substitution to plotman you can use SWAR which has been tested in Windows.