[Gameplay] Evelynn Passive Invisibility Indication for Player

On Summoner's Rift. Playing as Evelynn.

When I am on the Purple team, for the first couple minutes my Invisibility does not indicate that I am indeed invisible by making Evelynn transparent. I am not able to be seen by the enemy but at first I was unsure if I could/could not be seen. After clearing a camp, the transparency turns on.

When I am on the Blue team, the transparency indicates that I am currently invisible for the duration of the game.

What is the in game time, at the beginning of the match, that Evelynn is meant to go invisible due to her passive?