The back rower has no regrets regarding that decision and can't wait to experience the unique atmosphere and expectation that surrounds Heineken Cup rugby once again this weekend.
"The Heineken Cup is one of the reasons I came to Glasgow," said Holmes, whose side have won one and lost one of their two opening fixtures, just like the other three teams in Pool 2.
"This game on Friday night is just massive for our hopes of going on and qualifying for the knockout stages. It is exactly the type of game you want to play in.
"With Cardiff getting their British & Irish Lions back from Wales duty, and the fact they beat Toulon at the Arms Park in their last Heineken Cup tie, we know we are going to have to lift things again. But that is the way it should be in European rugby's top knockout tournament."
Holmes impressed in last week's 28-16 domestic win at the Ospreys and the 27-year-old is hoping his efforts in Swansea will be enough to see him secure a starting spot once more when the Warriors return to Wales in two day's time.
"It was great to get the start down at Ospreys and even better to play my part in a vital win for us. So hopefully I have done enough to stay in for the Heineken Cup tie at Cardiff," Holmes told the Glasgow Evening Times.
"The openside slot is the one I prefer. The competition for that jersey between myself and Chris Fusaro will drive us both on. The jersey has swapped between us and we both know that if we have a bad game then we will be dropped.
"I had my best match in a Glasgow shirt in the last Heineken Cup tie (against Exeter Chiefs). But although I was satisfied with my performance at the Ospreys I know I have room for improvement."
Glasgow will be without centre cum wing Sean Lamont for the back-to-back clashes with the Blues after scans confirmed ankle ligament damage following his injury at the Ospreys. Lamont didn't suffer a fracture as was first feared but he is still expected to be out of action for the next few weeks and faces a race against time to play any further part in the pool stages.
"Sean will require a further review with the consultant at Spire Murrayfield over the next few weeks to determine the length of time he will remain on the sidelines. A further update will be provided following this assessment," read a statement on the Glasgow Warriors website.
"Sean is an exceptional leader and such an experienced player. He is a talisman and it is obviously a big blow for us to lose him," added back row Josh Strauss. "Everyone in the team feels for him, but we've got good depth in that position so we just have to focus on the team that we have to play this weekend and hopefully pull it off."