Brennan said she was thrilled to lock in a rider of Shinn's calibre.
“It's a bit of a coup getting him,” Brennan told NZ Racing Desk.
“He's confirmed for the Fred Best and if the horse goes well we're hoping he will stick with him.
“He's booked to go over to Brisbane on Sunday morning and at this stage everything is going to plan,” she said. “He came through his Te Rapa run in really good order.
“The Queensland Guineas is a bit closer to the Fred Best than we'd prefer. We've been spacing his races, but we'll just see how he goes first-up over there.”
Vigor Winner sealed the Queensland trip with his dead heat for first with Speedy Meady in the Group Three Breeders' Stakes last Saturday week.
“I thought he'd just been beaten again in the Breeders' Stakes,” Brennan said. “We've gone so close so many times this season with our horses and just been beaten.”
One of Sydney's leading riders, Shinn has based himself in Brisbane for the winter carnival.