I'm not sure about down in Hakuba, but we're having a similar late start up in Hokkaido. I wouldn't worry too much. Looks like a big system is coming in Monday/Tuesday. And once it starts up, it doesn't take long for the snow to accumulate.
My local hill opened last Saturday, but then closed again as it rained so much. Not feeling too stoked right now with clear days in the forecast, but come next week things should be all good.