The scrum-half moved from Wasps to Glasgow in the summer in a bid to catch the attention of Scotland coach Frank Hadden.
With just a few games gone in the new season McMillan has done just that after being selected for Hadden's large pool of players for the November matches.
He faces a tough task to make the final squad and indeed a place in a match-day 22 with Mike Blair, Chris Cusiter and Rory Lawson also in the scrum-half frame.
However the sparky No. 9 is just pleased his move north has reaped rewards so early.
He said: "Playing for Scotland is the reason I played rugby at eight years of ageand nothing has changed. It's obviously a big ambition of mine.
"People have made a lot of my decision to move to Glasgow in order to challenge for a place in the Scotland squad but although that was a big factor I am still dedicated to helping Glasgow be successful."