Cadman has impressed the Giants over summer, putting his hand up for selection with four goals in a reserves practice match this month.
The 19-year-old has a body - 195cm and 93kg - already capable of competing at senior level.
But he sits behind fellow key forwards Harry Himmelberg, Jesse Hogan and Jake Riccardi in the pecking order as GWS set their sights on a round-one clash with Adelaide.
"Do we play four of them? Probably not," Kingsley told AAP.
"If one gets injured or one drops off in form and his form is strong then probably (he'll be called up) but it's always hard to put a finger on when.
"We won't just throw him in there for the sake of it but we won't keep him out for the sake of it either.
"If he's ready to go, he's ready to go. But he's here for a career, not (just) a first season of AFL or VFL.
"He's going to be a 12-plus-year player for us so we need to have that in the back of our minds as well."
GWS traded up in the draft order to secure Cadman, a product of Darley in regional Victoria, who made it known before the lottery he would be happy to move to Sydney.
The Giants are hopeful he'll be a long-term marquee player in attack after losing fellow high-end selections Jeremy Cameron, Tom Boyd and Jon Patton to rival clubs over the years.
Cadman's progression so far as a key forward - working against All-Australian defender Sam Taylor at training - has been positive.
But it is his defensive attributes that have stood out for Kingsley.
"His appetite to work and to learn has been great, so to watch him develop and be able to play as a key forward at AFL level over the summer has been really good," Kingsley said.
"His work in the contest and his willingness to chase a tackle and put pressure on, for a big guy, is going to be an absolute point of difference between him and all the other key forwards in the competition.
"He's really clever, he's very clean and he's got great skills so we're really excited about what he's going to become for us."
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