New bee boxes

I've been assembling  bee supers and frames.  They look so nice, all fresh.The idea is that if the bees are ready to swarm this year (so far they are thriving and vital, so I'm hoping for the best), that there will be a move-in-ready apartment conveniently right next door!My idea is to leave the bottom super empty, maybe a couple frames in the top box, to be spacious like a swarm box.  Since I haven't built a swarm box yet, I need to build supers anyway, and I want to have something ready in the event of a sudden swarm, then this is a better-than-nothing measure.I was assembling frames in my tiny camper, and stocking them outside, when the robber bees arrived.  They were doing their nervous, zigzag robber bee thing, investigating the new wax frames with enthusiasm.More and more bees arrived (they were uncannily camera shy though).  I started to get nervous, and promptly put up a box in the field for them to inspect.They haven't made any moves on it, but they know it's there.This has been such a drab, cold!, protracted spring, that there hasn't been a day warm enough for me to make a full hive inspection.  I feel like I should.  I am heartened that it takes a long time to find a Varroa mite on the bottom board, they are sucking back the syrup I give them, and they have at least doubled last year's numbers, judging by the comings and goings.  So far they seem to be caring for themselves quite well.  I hope I can give them a third super in time.