As I understand it, the bulb has enough stored 'food' to make one year's worth of growth(leaves). I'd plant the ones that have sprouted and let them grow their leaves. Hopefully they'll gain enough growth time to store food for next year and bloom at the proper time. The ones that haven't sprouted, you might put in the fridge but I'd get more info before doing that.

I'd plant them now. I planted some in a flower box about 1 1/2 weeks ago and they are coming up. What have you got to lose?

Its hard to store them properly for the amount of time it would take to get you to the right month for planting. They usually end up drying out and rotting.

They need a certain amount of cold to signal the plant to make a flower bud and bloom. For most tulips you have to plant them around Thanksgiving weekend to get enough cold to make flowers the following spring. But nowadays there are plenty of new colors that don't seem to be that rigid about cold.

If it is really important to you to get this group of bulbs to bloom you can either pot them up and shove them in your refrigerator for a month or pot them up and let them grow. If some of them bloom then great, if not then let them live as long as you can keep them happy and then let them dry up and appear to die. Take the dead looking plants in their pots to the garage or somewhere out of the sun where they can stay dry. The bulbs should last until fall when you can then plant them in the ground. If they only send up leaves you can usually keep them alive until the end of June or early July. You want to keep the leaves up and happy as long as possible.

Or you can just plant them in the ground and see what happens - you might get a few flowers. You never know what treatment they received before you bought them, they have enough chill hours already.