The club have avoided rushing into any recruitment decisions, despite Johnson's shock release to the Sharks at the end of last year that left a major void in the halves.
Coach Stephen Kearney on Thursday said that, at this stage, he was pleased with the progress of the young halves currently on the roster, leaving Harris-Tavita, Keighran and and even Hayze Perham in the mix for round 1.
Harris-Tavita has been seen as a player of the future for the last couple of years but his time may have arrived.
Keighran, who joined the Warriors from Penrith in the off-season, is yet to make his NRL debut but also showed plenty of promise in the lower grades at the Bulldogs and Panthers.
Perham is one of the clubs brightest prospects and Kearney has been impressed by his work throughout pre-season. But the 19-year-old is seen as an "outside chance" to start round one as he continues his transition from fullback to the halves.
"It's a big challenge in the NRL but he's making some progress," Kearney said.
"I think Adam and Chanel have both put their hands up over the course of the summer. Hayze is certainly another one too, they're three young men who obviously sense an opportunity."
Their first big audition comes in the Warriors' opening trial against the Storm on February 22 in Geelong.