After playing regularly during pre-season, the 18-year-old was named in the starting XI away at West Bromwich Albion in mid-August.
Despite the return to fitness of Saints' regular right-back Nathaniel Clyne, Chambers kept his place for the team's subsequent league matches before the current international break.
Now, speaking for the first time since the season got underway, the Academy graduate is focused on getting even better.
"It's been quite a mad first month to be honest, but I've enjoyed every minute of it," he reflected in an exclusive interview with Saints Player
"I've been getting games under my belt for the First Team, which is what I was aiming to do at the start of pre-season, so it's going really well.
"I just want to keep striving, doing well and pushing myself.
"When you get a chance, you have to take it – everyone knows that," Chambers continues.
"My debut was a great occasion. I had to focus on the game and I felt it couldn't have gone better, really. The fans were unbelievable and we got a good three points.
"When the final whistle went, it was the best feeling I've ever had. I think I went round hugging everyone and going mad, and then I went over to the fans to applaud them because they were fantastic during the game.
"It was just the best day of my life."
Chambers had a taste of senior football in Saints' previous pre-season, joining the First Team in preparing for their return to the Premier League last summer.
However, after featuring in a number of friendlies, he could not find a way to break into the First Team other than for a substitute appearance in a Capital One Cup match at Stevenage last August.
And Calum – who converted from playing in midfield to right-back over the course of last season – says that particular experience left him determined to make his impression this time out.
"I felt ready at the start of pre-season," he insists. "Last season I got so close but went back down to the Under-21s, and I think that step back has pushed me on and made me want it more.
"I had a little taste of it [last year] so this pre-season I gave it 110% to make sure I didn't lose it again."
With Clyne now in fine fettle once again, the pressure is on for Chambers to keep his spot when Saints return to action against West Ham this Sunday.
And the Petersfield-born youngster says he's enjoying the competition provided by his fellow right-back ahead of that game: "We're both fit now, so we're pushing each-other on to make ourselves better players.
"I think it's good to have competition in your position. We push ourselves in training and in games, and that will spur us on to play better.
"Hopefully I'll get more and more games under my belt and become more experienced."