Hello there,
I think, being kept in the fridge those tubers are like completely dormant. I guess that they start sprouting eyes after you kept them for a while at room temperature.

I splitt mine abot 5 weeks ago. I wasnt too fond of the 2 varieties so I wasnt too anxious. I used a realy sharp knife and diveded a big clump just by guessing roughly. Last year's dry stalks give you a rough idea where to expect eyes. I let the diveded tubers lie for about two weeks so the cuts could dry out nicely (no chemicals needed). Then I potted them in a sand/gravel/ pot ground mixture and watered once. And now after about 3 weeks of sitting around in my cool kitchen they all show some eyes. So if you want a sure bet, pop them in a box with sand/ pot ground ..., water VERY little, give them light and wait. They will sprout. And then you can divide them. But if you plant bigger parts/ tuber clumps, you get stronger plants in my experience.
And even really shriveld tubers of mine produced fresh roots and everything after beeing potted.

Well then, good luck,

cheers, Linaria

Just bringing them out of the fridge, unwrapping them, and giving them some warmth/light should bring the eyes out. Then you can divide. If you put them out in a sunny window with some soil the eyes should come out.

Check out this great thread for more help!

Here is a link that might be useful: splitting superthread