The Aston Villa midfielder, 19, is on the verge of playing in an FA Cup final, after helping the Midlands club reach the decider at Wembley with a come-from-behind 2-1 win over Liverpool on Sunday.
But whether Grealish - who started and played 84 minutes against the Reds - appears more frequently at the coveted London venue is up to him, as he prepares to decide on his international representation.
The Birmingham-born product has played at under-21 level for the Republic of Ireland.
Villa manager Sherwood revealed he has experience in dealing with such situations.
"I had the same situation with Nabil Bentaleb, who could have played for France but decided to pick Algeria," the former Tottenham boss said.
"I did have a chat with him and he asked me what to do. I just said: 'You've got to go with your heart. Do you think you're French or Algerian?'
"That's the decision he had to make and now Jack has got to make that decision."
Sherwood said Grealish needed to establish himself in the Premier League first.
"Jack has to play a few more times for Aston Villa before he needs to make that decision," Sherwood added.
"It's up to Jack where he wants to go. It's purely up to him. What I've got to do is make sure he's got that decision to make.
"He must be doing something right for Aston Villa if he's got those options. That's my priority.
"Then it's up to Jack to decide where he wants to go."
