How long has Twitch been able to recall while stealthed?

His Q lasts 10 seconds at rank one so he can do the whole recall while stealthed wherever he wants. That's a really dumb interaction.

Edit:

Just to clarify. Twitch, Shaco, and Eve are the only ones that can recall while stealthed, but Twitch is the only one that can complete the recall while still stealthed (Eve doesn't really count because she's getting a rework soon). Even though Rengar's stealth is just like Twitch's he cannot recall while stealthed.

None of the other stealth champs can do what Twitch does. Considering that Riot made the detection radius for Twitch really tiny, you have to be right in his face to actually see him recalling which is really dumb. If you're recalling in a bush and I ward it I should be able to see you and capitalize on my smart ward placement or your bad positioning, but with Twitch this isn't the case unless you are right up in his face which doesn't really seem healthy for the game.