Summer arrivals Dean Brill, on loan from Luton, and Vincent were handed first-team debuts for Inverness, while fellow new boys Ben Greenhalgh, Carl Tremarco, Danny William and Torbjorn Agdestein were amongst the substitutes.
Injury ruled out both Marley Watkins (ankle) and Curtis Allen (knee) for Caley Thistle, but Ryan Esson was included on the bench as he continues his recovery from a groin problem.
St Mirren made the trip to Highland Capital without the injured duo of Kenny McLean and David Barron, but there was a welcome return for Darren McGregor, who was making his comeback from a second serious knee injury.
St Mirren were unbeaten in three outings against Caley Thistle last season and they almost seized the initiative early in this one, Steven Thompson setting up Harkins, but his drive from 18 yards was turned away by Brill.
At the other end, Nick Ross connected sweetly with the ball from 16 yards as the visitors struggled to clear their lines only to see it comfortably clear the crossbar.
Vincent then gained possession just over the halfway before running 30 yards unchallenged, but he skewed his effort well wide of goal as Inverness looked to break the deadlock.
However, it was Saints who came closest to open the scoring just after the half hour mark, Jim Goodwin's 22-yard free-kick superbly touched on to the post by Brill.
After a first half of few chances, the second period began with a bang.
Aaron Doran found Billy McKay with a cross and he headed it down for Vincent to striker, but his goalbound effort struck the arm of David van Zanten.
Referee Kevin Clancy pointed to the spot and up stepped Vincent who beat David Cornell with a low effort into the corner to open the scoring in the 48th minute.
Barely 60 seconds later and Caley Thistle doubled their tally with the help of some slipshod St Mirren defending.
Danny Grainger's short back pass was chased down by Billy McKay. Cornell got their first, but his poor clearance landed straight at the feet of Doran, who from 18 yards produced a composed finish with the goal unguarded.
Inverness were now rampant and in the 59th minute they all but ended the match as a contest.
Doran's trickery created space for David Raven to swing in a teasing cross with his left foot that was wonderfully glanced into the corner of the net by Caley Thistle's top scorer last season McKay.
St Mirren made a double change with the introduction of Jon Robertson and Sean Kelly for Paul McGowan and John McGinn, but it did little to inspire any sort of comeback.
The Paisley club's disappointment was further compounded when van Zanten saw red 10 minutes from time, the full-back receiving his second caution for hauling down Ross having been booked for giving away the penalty.
Josh Meekings blazed a late chance over the bar, but by then the game was well and truly beyond St Mirren as Caley Thistle began the campaign in style with the comfortable