Just leave them. Keep them watered but not too moist, and as long as they stay cool, the sprouts shouldn't extend too much. Bulbs will grow roots after planting as well as sprouts, the sprouts shouldn't get too big until after a couple weeks of cold temperatures have passed.
If they look like they're getting too big maybe you could find a leaf pile to bury them in outdoors. That should be enough protection to take them through the winter.

Thanks Kato, I only have a balcony but I have a bunch of Christmas tree branches in my window boxes that I could pull down and cover them with.

In mild winters, I've had daffs start sprouting by Christmas, so this isn't horribly unusual. (I mean permanently planted outdoors daffs)

Daffodils are showing shoots here outdoors. They'll just sit it out until the conditions suit them. They are not fazed by cold.

Thanks, you guys! I was afraid to leave the window boxes outside here, in Zone 5. I've tried planting bulbs directly in my balcony window boxes, and they don't come up. Same with pansies I try to overwinter, they don't come back either.

So it sounds like I should just keep them in the garage and not worry about them. Hopefully they won't get too big. I'm still thinking I should probably cut back the watering to once a month or so.

If they freeze solid, they will usually rot and die. That's why you lose them in the window boxes.

I wish it were that straightforward but I think there's more going on than just avoiding freezing.
I have plenty of bulbs that freeze solid yet grow and bloom just fine... but I've also had plenty that rot in containers after looking healthy all winter. Maybe next fall I'll do a little planting experiment :)

I did try one experiment. I have an enormous pot, so I planted a couple of Iris rhizomes right in the middle, then covered the pot with a pile of Spruce branches. We'll see if they survive the Chicago winter!

If these puppies in the garage get any bigger I might have to bring them in the house as forced bulbs.

junebugapril - can you find them a cooler spot so they slow down? How tall are they exactly?

I'M in Montreal and are sitting in pots near a sunny window , standing over 12 inches. How unusual is that ? I do minimal watering

Are they indoors? And what sort of bukbs are they?