If you do end up putting it out in the snow, make sure to do it at night so as not to expose the quilt to UV light. And you probably want a drier snow (I guess that's maybe the idea behind it being the "first snow"), but I personally would be really reluctant to put a vintage quilt out in the snow, especially when it's a family heirloom.
For new quilts, I usually recommend that owners consider vacuuming the quilt more than washing it. You just put a nylon stocking over the hose & gently run it over the top of the quilt. It really does work! Here's a link to an article I read a while back about cleaning new & vintage quilts:
http://www.nationalquilterscircle.co...clean-a-quilt/