Johnstone, 25, has been out for two months after suffering concussions in consecutive games but he has been given the all-clear to play once more.
Wakefield boss Chris Chester says the England international will feature in Friday’s game at Warrington Wolves or against Castleford Tigers next Wednesday but it is unlikely he will appear in both.
“He has been out for nine weeks and we’ve got to make sure we do the right thing by Tom,” he said.
“Whether that’s play him on Friday and not Wednesday, or don’t play him Friday, but do on Wednesday, it is something we need to have a good think about.
“We have discussed it as a staff and we’ll make a call on Friday.
“It’s a short turnaround so we’ll see. We’re also mindful Tom has to go on Monday to an England session, so we have got to be mindful of his schedule between now and next Wednesday.”
Johnstone has not played for England since scoring a hat-trick against France on debut in 2018 but he is high in the thoughts of new national coach Wane who attended Trinity’s training session today.
The frustrating concussion setback means he is unlikely to be in the frame for their game against the Combined Nations All Stars on June 25.
But Chester said: “We have got to make sure Tom is in the best shape he has been in, to give him a really good chance of getting into the World Cup at the end of the year.
“That’s the target.
“The discussions we’ve had with Shaun have been based around some individuals within the club and what Waney wants to do at national level.
“I can't speak highly enough of Shaun; I’ve neve met a guy so passionate about the game and his country.
“It was a real eye-opener seeing him here sat with the staff and tipping us up and chatting with us about things he’s wanting to do at England level.
“There are players at Wakefield Trinity that are in and around the England team and certainly know what’s expected of them.
“Hopefully at the end of the year we could have a Joe Westerman playing for his country or a Reece Lyne or a Tom Johnstone and that would be a massive achievement for those individuals and great for the club as well.”
Meanwhile, forward Kelepi Tanginoa has not been ruled out of Friday’s game despite suffering a “really bad dead leg” in Sunday's win over Leigh Centurions.