Answer: The short answer to your question is that the bulbs need time to develop roots so yes, they should be potted up prior to the chilling phase. Here are some general guidelines for forcing bulbs:
After planting, place the pots in a cool, dark place, such as a cellar or refrigerator, to initiate root and shoot growth. Other suitable environments include an insulated cold frame, under a porch, or an unheated garage. Cold storage is a critical step in the forcing process. Ideally, temperatures should be 35-48 degrees F. If necessary, set boxes, pots or black garbage bags over your potted bulbs to keep them dark during the cooling period.
The medium should be kept moist through the rooting and cooling period. After five or six weeks, the roots should emerge out of the bottom of the containers of the large hardy bulbs.
Forcing will take about 12 weeks for the early-blooming bulbs (snowdrop, crocus, daffodil) and about 16 weeks for the tulips. Longer cold storage will result in taller flowers, while storage time shorter than 13 weeks will result in smaller plants and sometimes aborted flowers. A good rule of thumb; when you see the shoots 2-3 inches above the soil and fine white roots emerging from the drainage holes, it's time to bring the pots out of cold storage. At this stage of development, move the bulbs to a cool location such as an unheated entryway or closed off back bedroom, where the temperatures are in the 50's. Bulbs should be placed in indirect lighting and should not be allowed to dry out. Feed weekly with a half-strength solution of houseplant fertilizer. Turning the pots every day or so keeps the flower stems straight and strong. In a week or two, the stems will elongate and the buds will become plump.
When the foliage and buds are well developed, move the pots to a bright, sunny window in the house, where temperatures are near 65 degrees F. Once the flowers begin to open, take the plants out of direct sunlight to prolong the bloom.
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