The Raiders entered the pre-season with uncertainty as to who would play in three of four spine positions, but the biggest selection battle looming at fullback.
Sebastian Kris began 2023 at the back of the park but Jordan Rapana, Xavier Savage, Albert Hopoate, Jack Wighton and Harley Smith-Shields all started games there across the past two campaigns.
Veteran winger Rapana finished last season moonlighting as fullback but will be 35 and off-contract by the end of  this year.
Canberra will need to look elsewhere as Kris, predominantly a centre before last season, faces suspension for round one.
Stewart has been tipped as a genuine chance to hold the spot longer than just one game after an impressive 2023 spent mostly in the NSW Cup side.
The 18-year-old had his first chance in the top grade during Saturday night's 38-16 pre-season defeat of Parramatta and did not look out of place.
Xavier Savage breaks the line during Canberra's trial win over Parramatta in Sydney. (Steven Markham/AAP PHOTOS)
The game confirmed to Stewart he was ready to make it in the big league.
"I'm confident now," he said.
"I needed that first hit-out. I haven't had an opportunity in a trial (before) and obviously haven't had my NRL debut so that's definitely a confidence booster.
"I'm pretty keen to get that number one spot."
The speedy Stewart appears likely to spend more time at fullback when Canberra host North Queensland for their second trial match this Sunday.
As fellow young Raiders Kaeo Weekes and Ethan Strange prepare for the chance to become first-grade mainstays themselves this season, Stewart said his coach had encouraged him as he rose through the ranks.
"Me and 'Stick' have good chats," Stewart said.
"He doesn't sugar-coat anything so if you're doing something wrong, he'll tell you, if you're doing something good, he'll also tell you. He's a pretty straightforward guy.
"(But) you can do things wrong a million times and he'll still give you that chance, he'll give you that confidence. For me, that's really comforting."
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