The 22-year-old ended a seven-game barren run to make it 20 goals for the season to see off Dale at a packed Priestfield Stadium on Sunday evening.
Jackson had scored just three goals from open play in 2009 before kick-off, but opened the scoring when he converted Andy Barcham's low cross.
Chris Dagnall levelled just before the break but Jackson won it
from the penalty spot after John Nutter was fouled by Rory McArdle.
Stimson revealed that a TV pundit had suggested that his leading scorer could be left out in the League Two semi-final second leg, but the Gills boss never even considered that.
"Rochdale are a good side," he said. "We've had some close games with them and at the end of the day, it needed a bit of magic and the kid's certainly got it in his feet.
"He's had a bit of a lean spell but the kid's a goalscorer and he will produce when he needs to and he's done that today.
"He's a model professional who one day will play in front of 10 or 20,000 every week and get his name sung from the first minute to the last."
Almost 10,000 fans turned out to watch the clash, and Stimson - who was unable to save the Gills from the drop last season - believes that shows the potential of the club.
He added: "This club is geared for League One, if not better, but it's getting there first. The fan base is absolutely huge, you've seen that today.
"I hope they all save up and get themselves down to Wembley because it's a fantastic stadium and the more Gillingham supporters, the more noise, the more chance we've got of winning."
The Gills will now face Shrewsbury - who beat them 7-0 back in September - at Wembley on May 23 and Stimson believes the showpiece final is a just reward for his hard-working players.
"I'm very happy for the players," he added.
"They've put a lot of hard work in this season.
"The majority of them came back on the first of June - some of them weren't too happy because I cancelled a lot of their holidays, but you get your rewards if you're prepared to do that
little bit more.
"Now they've got their big reward by going to Wembley against a good Shrewsbury side we know about and we look forward to it."
Rochdale boss Keith Hill refused to be downbeat after the defeat, but conceded that there may need to be changes at the club over the summer.
"There's a lot of soul-searching to be done throughout the course of the summer," he said.
"Not just from me and Flicker (assistant boss David Flitcroft), but from the board of directors, the chairman and the players themselves.
"I thought the performance tonight was outstanding. There was commitment from all the players to be successful, there was a belief there and we've gone out to a penalty. I think it was a penalty, I'm not complaining at all.
"There's a lot of emotions in that (dressing) room because we weren't expecting to go out tonight.
"There's unbelievable belief in there and that's why the emotions are so low because at no time did we ever expect to be in this position.
"I give all the credit in the world to Mark Stimson and Gillingham, they're going to Wembley and it's a shame that we aren't."