Average Lucid Dream Length?

What is the average length for a first time Lucid Dreamer?

I'd say from 1-40 seconds? Not quite sure.

I had my first the other day and it was like 2 hours long, but it felt a lot longer in the dream because time is like different there.

There is no average because no real tests have been done. If you haven't had a lucid dream yet then expect it will last a long time. If you go in expecting it to be short it probably will be.