I would start them now, planted in gallon pots, and hope that I could get them out to the daylight by the time they send up green shoots. If you can time them to get a good root structure going before your frost free date you will gain some time on them. I always do this but usually plant them outside in April. Here they can be planted outside at this time, so I usally do this with fall purchased lilies and the callas. Spring purchased lilies go directly in my garden.

Forcing time for Stargazer lilies is 100 days. If you don't have a greenhouse, I would not recomend starting them until a little later this month in zone 5.

Plant them at least six inches deep in your soil medium. Don't use planting medium containing perlite or superphosphate. Water the container thoroughly after planting, and keep the soil moist but not wet.

Assuming you are using supplemental light in your basement. It is recommended that you use high pressure sodium lights for at least four extra hours every day.

Lilies don't mind growing cool. They actually prefer this. Night temperatures should be around 63 degrees, and day temperatures at 67 degrees.

You should see the "lily noses" poking out of the soil right around four weeks. Be certain the lily shoots stay dry at all times. Lilies are susceptible to botrytis -- especially the oriental one such as Stargazer. Oriental lilies are also susceptible to aphids when it is damp, and they don't receive enough good lighting. The lily Starfighter has been bred to be less susceptible to disease. It is a beautiful oriental lily as well.

Wishing you well with your lily venture.