I've often said that if you watch just the first scene where Brian meets Justin, you could predict the arc of their relationship, that Justin was about to change Brian's life completely.
"That's when it happened. When he came along."
There are a number of moments when it's possible to say, THIS is when Brian knew he loved Justin, this is when Brian loved Justin, this is when Justin loved Brian, this is when Brian accepted that Justin loved him, this is when Brian accepted that he loved Justin.
But I don't think there can possibly be any argument at all that in the first three episodes, Brian was well and truly fucked.