Now is the time to plant for Spring beauty!
CSU Extension has a great guide to planting fall bulbs here.
Quick summary:
Crocus, snowdrops, species tulips, dwarf iris and Siberian squill (a type of iris) are very early bloomers. Next are grape hyacinths, tulips, daffodils, fritillaria and common hyacinths. Tulips are not deer resistant but the others are. If you want tulips plan on putting a netting over them to keep the deer away.
Late spring to early summer bloomers include alliums, bearded iris, and Dutch iris. Careful planning can lead to an outstanding bloom display from early March through early June. Deer may eat alliums even though they are in the onion family, so plan on using a net or protective apparatus for alliums (they're tall).
While you are planting spring blooming bulbs, consider also planting fall blooming bulbs to round out your garden. There are more than a dozen species of crocuses that bloom in fall and winter.
Another lovely fall bloomer is Colchicum (shown in photo above). Colchicums are similar to crocus, but they have broad leaves that grow briefly in the spring and die by midsummer. In the fall, leafless flower stalks produce clusters of large purple flowers. (Do not confuse these with the edible saffron crocus as most parts of the Colchicum plant are poisonous.)
Rounding out the list of hardy bulbs to plant in the fall are daffodil, snowdrops, Spanish bluebells, Winter Aconite, and Sicilian Honey Garlic (can be a little invasive so take care where you plant them).
Many bulbs naturalize, meaning they will multiply and spread over the years with little effort on your part. Bulbs can also be lovely tucked into little spots in flower beds, in lawns or meadows, around trees or even in rock gardens to add a splash of color in the spring.