If you have a mind open enough to understand that we can't be the only life in the universe, then you must also be smart enough to understand that we can't be the first, considering that we are only a young specie compared to the age of our galaxy, let alone that of this universe, or other possible universes. On some planets, maybe even suns(yes, I said Sun - who told you that all lives are corporals) their might be better conditions for life - some form of it we might not even comprehend. While you ask the question when will we discover Alien lives, you also ask the following: Have we already been discovered?