Kevin Nolan handed debuts to four of his new recruits, with David Vaughan, Thomas, Boldewijn and Kane Hemmings all starting the match.
Richard Duffy sported the captain’s armband and was partnered in central defence by Shaun Brisley, while Jon Stead was the man to start up front with Hemmings.
Notts claimed the first chance of the game on four minutes when Boldewijn was denied a dream start by Dillon Barnes, who tipped his low shot round the post.
Colchester responded by winning two corners in quick succession, the second of which saw Brisley block a goalbound header with his body.
Thomas was then presented with an excellent opportunity to open his Magpies account when the ball dropped kindly for him following an Elliott Hewitt long throw. He didn’t connect properly with his volley, however, and the chance was gone.
Franck Nouble flashed a header across goal and wide before Dan Jones collected a yellow card for a foul on halfway as an even contest continued.
Thomas then saw an effort deflect out for a corner, Brisley glanced a header into the side-netting and Boldewijn struck the ball across goal and wide from the corner of the area.
There was still time before the interval for Duffy to find his way into the referee’s notebook for a cynical foul on ex-Magpie loanee Aaron Collins.
But that was to be the final action of note in the half.
Notts reemerged unchanged and Thomas led the charge for an opening goal, storming his way towards the United area with a run which resulted in a corner for the hosts.
Hemmings saw a shot deflected off-target before Ross Fitzsimons was forced to tip a cross over the bar at the other end.
Harry Pell wrote his name into the book for a foul on Thomas who, three minutes later, came agonisingly close to opening the scoring when he controlled Duffy’s pass on his chest before drawing an excellent save from Barnes with a looping effort from the edge of the area.
Stead made way for Dennis on 69 minutes and, seconds after his introduction, he probably should have seen his side fall behind when Nouble picked out Collins in acres of space – only for the forward to lose his footing at the vital moment.
Vaughan, later given Man of the Match, was then booked after deliberately blocking off Collins moments before Notts were given their biggest scare of the day when Tom Eastman curled an effort off the crossbar.
A minute later, however, it was Notts’ turn to go agonisingly close to scoring when Boldewijn’s brilliant low cross from the byline was steered over the bar by Dennis, who had slid in to meet the ball.
Hewitt’s name was taken when he was adjudged to have fouled Mandron and Ryan Jackson drew a comfortable save from Fitzsimons as the clock ticked down towards full-time.
And, four minutes after Terry Hawkridge replaced Thomas, the referee called time on the opening game of the season.
Notts County: Fitzsimons, Tootle, Duffy, Brisley, Jones, Thomas (Hawkridge 91), Hewitt, Vaughan, Boldewijn, Stead (Dennis 69), Hemmings (Alessandra 83).
Booked: Duffy, Jones, Hewitt, Vaughan.
Colchester United: Barnes, Kent, Prosser, Eastman, Jackson, Pell, Lapslie, Dickenson, Collins (Mandron 76), Szmodics, Nouble.
Booked: Jackson, Pell.