Malthouse said he watched Thursday night's Carlton-Richmond clash with great interest as Brett Ratten and Damien Hardwick wrestled with the new rule.
He said he had "an idea of when to pull the trigger this week", but would review the process again after this weekend.
"Is it right? I don't know. That's why I'm going to let everyone else have a crack at it first and then come back and review our system," Malthouse said.
"I think it is pretty well documented most clubs will be reluctant to do anything before half time.
"The third quarter becomes an interesting one. I'm not sure what the stats are in regards to injuries; they seem to happen early in each quarter. so can you get through the first few minutes of the third before you start to get the wanders in regards to where you're going to place a player?
"It will be a very interesting first round to find out when clubs make the change, how many were compulsory - as in injuries - and how many were a substitution to perhaps relieve a player of his duties who may not have been travelling as well as the coach thought.
"I think we need to get through round one, and even then there's still going to an uncertainty about it."
Malthouse also said he expected plans to be affected by the game's unpredictable nature, as when Carlton's Jarrad Waite became the first player to be subbed after he received concussion on Thursday night.
He also had reservations over the new concussion guidelines and believed the introduction of the rule was more of a reminder to clubs to ensure player safety was paramount.
"That can throw a spanner right in the works and that's what took place last night," he said.
"If that was going to be tested we didn't expect it to be tested in the first game.
"I think the rule was always in place - most doctors would ensure that players' safety was first and not [let them] go back onto the ground."
Leon Davis failed to take part in Friday's final training session ahead of Saturday's match against Port Adelaide.
"He's got a heavy cold. I suspect that he should be okay, but if he's not, he's not," Malthouse said.
Malthouse said Nick Maxwell was training hard in his bid to return from the heavy knock he sustained in the NAB Cup semi-final while Tyson Goldsack needed some game time in the VFL before being considered for senior selection.
He expected Port Adelaide to present a strong challenge as the team had demonstrated it was playing for club legend Matthew Primus.
"They've got big-bodied centres and they're not going to be an easy pushover at all," he said.
"I've got the utmost regard for some of those blokes in there; [Dominic] Cassisi, [David] Rodan, [Robbie] Gray, [Steven] Salopek, [Matt] Thomas.
"They're all big bodies, they're all equipped with AFL football, there's no kids going through there that may be exposed to the bigger bodies of Collingwood.
"They've got a wonderful ruckman, a very good midfield and we've got to give them the respect they deserve.
"They've finished off on a high, they've won their past two practice matches by an average of 90 points, and that spells danger to me."
