So sorry for late response, busy day.
I picked 2 seconds intentionally. I wanted a number that was not so long as to be staring, but long enough that it would be clear it was intentional and not something someone was trying to hide, or accidental.
While your answer about "treat it like the sun" does make sense when accessing where the line is I am particularly curious about this case. More important how it would make the woman feel, would she feel attractive and liked, or would it make her feel bad for some reason i dont fully understand (but instinctually adhere to I guess).