What's the best time of day to use my light?
Most people find that light therapy in the mornings works best so, if you are just starting out, try this first. After a week or so, if you're not feeling much different, try introducing another session in the afternoon.
If you don't have time in the mornings, then using a light in the afternoon will still be better than not using one at all. Try not to use your light late in the evening though (i.e. within 3 hours of going to bed) as you may find it difficult to get to sleep.
If you have trouble waking up in the mornings then you should definitely use a dawn simulator. If this isn't enough, then use a light as well even if you only have time for a 10-minute rather than 30-minute session, and again top up later.