The pair were team-mates at Arsenal before the Polish goalkeeper moved to Turin in 2017.
"We talked to each other a couple of times before he signed for Juventus. He asked me for some advice," Szczesny told Gazzetta dello Sport.
"I told him: 'It's easy. If Juve call you, you can only say yes'. That's how it went and it means Aaron listens to me.
"He's had five months to prepare and he's already picked up a little bit. When I took him to dinner, he said more than just a 'hello'.
"He partly understood me and that's a good basis to work from. I'll take care of the rest to give him a hand."