Ady Pennick will now bring his first team to play at Shepherd Neame Stadium on Friday 7 July.
The fixture will be the Gills' opening friendly and give their fans the chance to see the team's new signings in action for the first time.
The 7.30pm kick-off will also give Lilywhites an opportunity to see Ray Turner's newly expanded squad for the 2017/18 campaign.
Gills agrred to the match to mark the opening of the new changing room pavilion - the first phase in Town's exciting stadium rebuild project.
Ray Turner urged fans to put the new date in their diary and fill the stadium.
He said: "We're delighted that Ady is bringing his first team squad to play against us, and I would like to thank him for the gesture.
"I hope supporters will turn out in numbers for what will be a wonderful Friday night occasion.
"It will be Gillingham's first pre-season match, so the first chance to see their squad ahead of the new season."