Instead, it is the prospect of coming up against Lee Mair, just eight days after his former team-mate left the Paisley club, that will bring about that air of familiarity.
McGinn cites Mair as a hugely influential figure in his career, the player 14 years his senior helping him to take his first tentative steps in the game. That they will now be on opposite sides in such a vital game for both clubs, as they look to move away from the SPFL Premiership's play-off spot, will be a strange experience for the 19-year-old.
"It is a quick return for Lee and it will be interesting," said McGinn. "We know his strengths and weaknesses but he also knows ours. It will be strange playing against him, almost like a training game.
"He's been a big influence for me. He was brilliant for advice and I will always be thankful for that. It is always good to get advice from the older guys and I was sad to see him leave. If ever I was feeling tired and not playing to the form I wanted then he would speak to me.
"I would be frustrated when I was in and out of the team. But he would tell me to be patient and that I had a great opportunity here. He took a lot of interest in the under-20s games last season and he has been a big help to all the young boys at the club."
St Mirren approach the match in eighth place but could be replaced there by Thistle should other results go the way of Alan Archibald's side. McGinn knows there is little margin for error over the coming weeks.
"We know how important the game is and we have to win it and push on up the league," he added. "We want to be looking up rather than down and we don't want Partick Thistle to overtake us. Hopefully we can push away."
Danny Lennon, who still wants to add to his squad in the final week of the transfer window, hopes to take inspiration from Ross County's successful surge up the table in the second half of last season. "You look at County last season sitting second bottom then 10 games later they're up in fourth," said the St Mirren manager. "If County can achieve it, why not us?"
The questions asked by Thistle of late have not been quite so optimistic. The Glasgow side occupy the play-off spot and have been left to figure out a way to arrest a run of results which has included just one win in 14 matches. A victory this afternoon could be enough to force a revival during the second half of the season and it is an ambition which was detailed plainly this week.
"It will give us confidence for the next few games if we can take points from this one," said Conrad Balatoni, the Thistle defender. "I haven't really looked at the table but we know that if we win then that can take us above them. That has to be our aim now."
Thistle have at least had some help plotting their route past St Mirren, with Mair having wasted little time in giving his new side the benefit of his inside knowledge. "As soon as our game finished on Tuesday, Lee started speaking about this one," added Balatoni. "He was just talking about the way they play, their threats . . . but we will keep that in house."