Clap/lay/set eyes on sb/sth British informal
To see or look at someone or something for the first time
I loved that car from the moment I clapped eyes on it.
I disliked Linda the minute I lay eyes on her. But now we are close friends.
I loved my wife the minute we set eyes on each other.
There is no clear origin of the idiom.
If you fall for someone's trick the first time then they are at fault.
Are you going to mess with me again? Fool me once, shame on you; fool me twice, shame on me.