Which ones are OK?

He's a friend from childhood.
He's a friend since childhood.
He's been a friend since childhood.

Question

Which ones are OK?

He's a friend from childhood.
He's a friend since childhood.
He's been a friend since childhood.

Answer

all three are weird

Answer

Hi Pelin 🙋🏻‍♀️
I agree with Josh, "He's a childhood friend." is a great option. I'd also suggest trying "He's been a friend of mine since childhood." 
While the third works, "of mine" is a nice and common way to use the phrase as well.

Answer

Out of those, I would say "He's a friend from childhood ".

You can also say "He's a childhood friend".