Originally Posted by
drowelf
I generally wait for the double-ding of passing through 10K before I drag mine out. At that point its ok to turn it on and get to work!
That's fine, but you don't have to wait that long if you don't want to. Once the airplane is off the ground you can bring out your laptop, lower your tray-table, and get to work.
The only reason why you have to stow it earlier on landing is because the F/As have to verify that everything is stowed before taking their seats for the landing. They do the pre-takeoff verification during taxi-out so no need to wait after takeoff.