Cummins will miss the first Test against England in Perth on November 21, after scans last week showed a hot spot in his back had still not entirely cleared.
Serious questions remain over Cummins' involvement in the series at all, with the quick having previously said he'd want to be bowling at least a month before his return.
Speaking on Thursday to announce he would play BBL matches for the Sydney Sixers after the Test summer, Starc said he did not know the latest on Cummins' fitness.
But he insisted the leader of the pace cartel had remained in "good spirits" and "ultra positive", while confident Cummins would not need a long lead in once cleared.
"I found one thing playing with Pat and being close with Pat, he doesn't need much," Starc said.
"Whether it's he bowls three warm-up balls and first over the game he's on the money.
"He just knows when to switch on or how to switch on really quickly.
"Whatever it looks like for him in his prep, it's going to be certainly different to what mine feels and looks like. That comes with experience and age."
Cummins' injury is likely to leave Starc, Josh Hazlewood and Scott Boland as the fast-bowling trio for the first Test at Optus Stadium.
Starc and Hazlewood have indicated they intend on playing all five Tests, with gaps of at least eight days between the first three matches helping their cause.
Beyond the trio, Michael Neser is the only other fit paceman with Test experience with Jhye Richardson yet to return from a shoulder injury.
Sean Abbott has been on the fringes for several years, while Brendan Doggett and Fergus O'Neill have also made strong cases.
"It's times like these you might unearth someone," Starc said.
"I certainly think there's enough experience around Australian cricket.
"There's obviously guys at different levels, different age groups, guys that have been in and around the squad a fair bit.
"You mention Ness, Sean Abbott's been around the squad for a while ... I know there's been a little bit of noise around Jhye Richardson coming back."
Starc himself will play one Sheffield Shield match before the first Test, with he and Hazlewood to bowl for NSW against Victoria at the SCG next month.
The pair will also play for Australia in the three ODIs against India before that, while Hazlewood is also in the squad for the first two T20s.
Starc said that one Shield game was ideal preparation, given he would not have been able to have a proper rest from bowling if he played in the Blues' season opener against Western Australia last weekend.
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