Trimble suffered significant damage to his toe ligament in Ulster's GUINNESS PRO12 match against Glasgow Warriors in October and has been ruled out of action for a number of months.
Gilroy had struggled to get game time at the Kingspan Stadium ahead of Trimble and Tommy Bowe, starting just three league games this season.
However, the 23-year-old impressed as he won his sixth international cap in Ireland's 49-7 win over Georgia in Dublin on Sunday.
And although Gilroy acknowledges it has been an uphill battle to dislodge Bowe and Trimble for club or country so far, he is determined to make the most of every opportunity without sacrificing a team-first mentality.
"Those guys are playing very well, Andrew is injured at the minute but I have to take my chance when I get it and show what I can do," he said.
"You obviously want to put your hand up and show what you can do but at the same time you need to play in a way that helps the guy beside you.
"It is important to get that happy medium right and I wish I'd have got my hands on the ball more [against Georgia] but in terms of a team effort I tried to do what was best for the team.
"I really loved every minute of being back in Dublin and playing at the Aviva but I wish I had got my hands on the ball a little bit more.
"Sometimes it is not all about the glamour - you just have to roll the sleeves up and do the hard work.
"That's what Joe [Schmidt] was looking from me in training this week - chasing ball and making tackles."
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