Hi ptosis, being a stealth unit, and the fact that they conducted taxi testing would lead one to believe there are a couple of possibilities.
A: It could be a bluff and not ready to go yet with the taxi testing being used as a visible deterrent to the rest of the world.
B: As mentioned on a few technical forums, it may already have the capability of being airbourne. Some of the more knowledgeable people in the aeronautics industry have queried taxi testing on an aircraft which has not been test flown yet.
Personally, I would guess that it will be well within the five years.