The Swiss driver will make a return to Supercars at the Great Race this year, partnering rookie Kai Allen in a Dick Johnson Racing-run wildcard entry.
She was set to jet to Australia this week to begin a compact testing schedule that was meant to include running on both the fourth and fifth of September, followed by a third test before Bathurst.
However those plans have now changed after de Silvestro underwent emergency surgery to have her appendix removed.
She is currently recovering in Switzerland with her travel to Australia delayed.
That has forced the team to scrap its September 4 test, while the test on the fifth will go ahead with Allen at the wheel.
The rest of the testing programme will then be adapted once de Silvestro is in the country.
"Simona de Silvestro was due to land in Australia later this week ahead of wildcard testing at Queensland Raceway on the fourth and fifth of September," read a statement from the team.
'However due to an emergency operation required to remove her appendix over the weekend, her arrival date in Australia has been pushed back.
"Simona is recovering well in Switzerland and at this stage is anticipated to join the team in Australia in mid-September. Alternative plans are being arranged for wildcard testing ahead of the Repco Bathurst 1000.
"The Shell V-Power Racing Team wishes Simona a speedy recovery and looks forward to seeing her soon."
There will still be some testing action on September 4 with Blanchard Racing Team to run its Jake Kostecki/Aaron Love wildcard at Winton, while Grove Racing enduro signing Kevin Estre will have his first taste of a Supercar at the same circuit.
All 11 Supercars teams will then test on September 5 as preparations for the Sandown 500 and Bathurst 1000 ramp up.
Queensland Raceway will host DJR, Triple Eight, Matt Stone Racing and PremiAir Racing, while Tickford Racing, Walkinshaw Andretti United, Grove Racing, Erebus Motorsport, Team 18, BRT and Brad Jones Racing all running at Winton.
