First of all “Welcome” to beekeeping, this forum n using a Flow-hive ! Your plan seems fairly right on but I’d up the bee coverage to more to approx 80%. It’s just a close estimate so your bees get one section (box) close to full before moving up stairs to the second floor.
Your bees have a lot of work building n drawing out 16 frames before even thinking of the Flow-Super. Living way north n your May later start … watch your bees draw out very straight comb or you’ll have to rework by hand to keep straight … that’s if you go foundationless … I personal didn’t n don’t… There are both thots on foundation or “less” ! I have a mix of wire reinforced n wax coated plastic which doesn’t come with Flow-system …
I’d connect with a local club or at least a beekeeper or two n get there local slant/thots/opinions. Use this local info as a guide not total truth as we all have slightly different ideas. Some are from local Wx/conditions/other. I’m really doubting you’ll use the Flow-Super because your girls have a lot to do to built comb n get the honey supply (60 to 80 lbs) to winter over in a cold/icy environment like yours… I’ve been at the Flow-system for two season without a Flow-Super harvest. This was do to short first season then a combo of varroa mites n dreath my second season (2017). I’m not discouraged n looking for season 2018 to be it or at least better.
I have two Flow-hives ( a 6 n a 7 frame ). The other four are traditional Langstroth hives that did no better in there shallow upper honey supers than the Flow. Local flowers, weather n other regional issues might allow you faster or slower harvests. Just keep on keeping on, learn from your bees, mistakes (we all make them), keep records so you can be knowledgeable about your colony n keep improving.
n again welcome,