The 24-year-old joined the the Hoops from Reading over the summer after Liverpool failed with a last-minute move to hijack the deal.
"I don't regret the decision I have made up to now," McCarthy told the Daily Mail. "Harry was a big part of me coming here. The things he said to me swayed my decision. I spoke to both managers and everything the gaffer here said to me I liked, and that's why I'm here now."
"Coming to a new club you want to get your first game under your belt and I'm over the moon to get that first game out of the way. The main focus for me now is to keep training hard week in, week out and give the manager a decision to make."
Queens Park Rangers continue their Premier League campaign when they face Aston Villa at Loftus Road tomorrow evening.