How did they arrive..........dormant, sprouting, roots growing?

After digging up Cannas and before shipping or replanting, I keep them in moist wood shavings.

If yours are still dormant, just place them in a cool, dark place.

I would actually get them potted and started. Our springs are sometimes too long and chilly (but falls are long and warm) and if we can give them a headstart now, they will have a better chance at blooming earlier in summer when finally planted out (been there done that). This is assuming you have some peat or potting soil and some small pots to stick them in. Even sticking them in some slightly moist peat in a zip lock and placing in a warm spot can help get them sprouted while you wait.

Otherwise if you would rather store and try to keep them asleep, annz's advice is right on.

If you plan to plant them in a week or so, they should be fine just stored in the house in the box they arrived in. I often get large orders and have had them in boxes in the house for a month. Due to the size of my orders, it sometimes takes me that long just get them all planted. They may sprout a little in the box and that's fine. Just watch for decay and bugs.