It will be the 10th time she has ridden her horse, Milli, on the cavalcade’s heavy wagon trail, but her first time as its head wrangler.
The person originally appointed to that role had suffered an injury, so Mrs Cooper was the replacement.
It involved making sure everyone knew the rules, especially when dealing with the wagons, she said.
"Wagons have the right of way.
"There are a couple of steep pinches where we may have to uncouple the horses."
Mrs Cooper and her colleagues did a reconnaissance run along the trail in a ute two weeks ago.
"I’m a little bit nervous. I’m supposed to remember everything."
The Les Webb Memorial Heavy Wagon Trail for this year’s cavalcade, the 30th in the event’s history, has 92 participants.
It is the only trail where everyone takes their own meals for the week, and where horses are penned individually at the end of each day.
Mrs Cooper will be riding alongside the wagons.
She has owned Milli for 16 years, since the horse was aged 2.
"She absolutely loves it," Mrs Cooper said of Milli taking part in the cavalcade.
"She goes from a lazy little troll at home to being at the front of the trail."
Because she was "always up front" thanks to Milli, it made sense to step in as the chief wrangler, Mrs Cooper said.
The trail’s riders and passengers are meeting on Saturday at Avenal Station and will head out across the station the following day.
They will cover an average of 20km a day, descending to camp at the Beaumont Hotel on Wednesday, March 1. A group party with optional fancy dress is scheduled there.
The Thursday is a planned lay day when local activities such as jet-boating can be enjoyed, then on the Friday the trail continues up the Millennium Trail to Millers Flat and its final camp.
A carnival day, final grand parade and hoedown will be held at the Millers Flat sports ground from 10am on Saturday, March 4.
The arrival of all the trails will swell the township’s population by about 400 people.
"Millers Flat is going to explode," Mrs Cooper said.
"I hope it’s got plenty of ice. It will be hot, I would think."
The cavalcade began in 1991, retracing the 1862 journey of Cobb & Co Coach’s journey from Dunedin to the Dunstan Goldfields, via the Dunstan Trail. The inaugural event attracted 220 riders.
Mrs Cooper hoped the North Islanders booked to participate would be able to travel south after the Cyclone Gabrielle disruptions.
She was due to be in Hastings for the Horse of the Year show just two days after the cavalcade finished, but did not yet know if the event would go ahead. Hastings was one of the areas hardest hit by the cyclone.
Mrs Cooper was going as a spectator and to help a friend with a stallion.
