If there's no problem of storing them, then waiting for the time the planter feels more like working in the soil is fine. Don't let them dry out...in fact, water them well in their pot, let them drain and keep them out of direct sun.
When you plant them, if the weather is still not warmish, then just give them a protective mulch to keep the cold off them.
One of the best defences against frost is a spray of water.
Newspaper, loosely fluttered over them, tied down with soil or a brick to prevent them blowing away, can protect against frost.
If you are near a large body of water....such as Lake Michigan, or Lake Superior, frost is not so severe as areas inland. A garbage can or a bushel basket over them, with a few evergreen boughs or leaves can prevent frost touching down.

Take heart...spring is on the way...albeit its a bit slower this year....you had snow.....
we had it in Ontario too....just north of Toronto..a blizzard for about 5 minutes...but it didn't stay...they're promisng 60's this weekend so that'll be a good time to get out and plant and I've made plans to do just that.

Clematis appreciate their heads in the sunlight but their feet in something approaching shade...a small plant in front can do that. A rock of size cools the soil at the base. Clematis like their soil slightly alkaline..so a scattering of wood ashes or lime into their soil can help.
Just don't let the lime be in touch with the roots.