Your spin-time can (and will) vary. However, I'll leave you with the guesstimates below. These are based on my personal experience, and observation of other people testing the Lambda. If you can't seem to hit the numbers below, give it a little more "wax on, wax off!" That means "practice" in case The Karate Kid was after your time. Not the new one, the old one :)
6 Minutes: Most people should be able to hit this without trying too hard. You have to have a good surface where the top can actually stay on it for that long. Try a plate or bowl to keep your top from falling off the table.
8 Minutes: Put in a little practice and 8 minutes can be reached...some of the time. This was the first big milestone. To go past 8 minutes you have to have a good surface...and good technique. At this point I can break 8 minutes almost every time.
10+ Minutes: If you practice a lot, you'll start seeing spins over 10 minutes...but that isvery hard to do. Even now, I might get 1 out of 5 spins that are over 10 minutes.
Just keep in mind that trying for a long spin is one way to enjoy your Lambda, but it's not the only way!