Even though Queensland picked Slater for Wednesday night's Origin match a little more than two weeks after he suffered the injury, Storm coach Craig Bellamy says the original diagnosis of a four to six-week layoff is "pretty accurate".
"He's still a little way away, but hopefully not too far," Bellamy told reporters on Wednesday.
Slater ruled himself out of the Origin decider late last week when he failed to recover from the posterior cruciate ligament strain he suffered in the second game on June 13.
The best scenario would be a return for the Storm next week against North Queensland on July 14, but he might have to wait until as late as round 21 against St George Illawarra a fortnight later.
While Slater did not train with the Storm on Wednesday, centre Will Chambers is back with the squad as he recovers from a rare blood clotting disorder.
Bellamy says the club is still hopeful Chambers can play again this year, although he said the 24-year-old's health is the priority.
Chambers was ruled out indefinitely in early June after being diagnosed with idiopathic thrombocytopenia, which could have cost him his life.
Bellamy says specialists are happy with his progress.
"While ever they don't want him to play or train, he won't be, but he is starting to do a little bit of training with us. We see that as a good sign," Bellamy said.
"Hopefully he'll get some footy in before the end of the year.
"There's still a bit of time ... our main emphasis is on his health. Until that is 100 per cent, we won't even think about him playing."
As the Storm's second-highest tryscorer for 2012 behind Slater, Bellamy says Chambers has been a big loss, which has been accentuated by Slater's absence at the back.
With centre Dane Nielsen called up into Queensland's reshuffled backline to replace Slater, Bellamy concedes the Storm could be pretty thin out wide against Canberra at AAMI Park on Saturday.
Bellamy was hopeful Nielsen would back up for the match against the Raiders, but plans to give his Queensland Origin stalwarts Cameron Smith and Cooper Cronk a rest at some stage over the next few weeks.