Hi,
In my experience they are best planted in the spring, but they can be planted in the fall, cover them lightly with soil. If they are bulblets you can plant them now and they should sprout a single leaf and begin to bloom the next year. If they are seeds the will send up a single leaf the next spring and begin to bloom the 3rd year, although I have had seed bloom the 2nd year. The seed requires about 2 months of chilling to sprout so it is easiest to plant them and wait. With the tiger lilies I know that once the bulb gets going it will spread fairly quickly giving you a good sized clump in fairly short order, they can double their numbers yearly. They will also produce stalks covered with the bulblets for you to plant out if they are not big enough to bloom. I have no trumpet lilies so I am not sure about them, but I would guess they would be fairly close to the same. I am sure there are lily growers on here who will give lots more info

Trumpets are easy Epigeal or "quick-type" seed to start, you can sow those right now, make sure you keep an watchful eye on watering.
Tigers are easy to start by Bulbils.

Here are a couple of websites that may help you.

http://www.lilies.org/growingfromseed.html
http://www.mikesbackyardgarden.org/lilyprop2.html

Goodluck

Sharon