Less than 24 hours before the start of the deciding match in this record-breaking series, Bairstow was contemplating how to try to kick-start Yorkshire’s NatWest T20 Blast campaign at home to Nottinghamshire.
Within minutes of him taking guard on Saturday, in pursuit of a Duckworth-Lewis target of 192 in 26 overs, the hosts had sunk to 45-5.
Yet another hour later Bairstow was celebrating a famous three-wicket success - and 3-2 series scoreline - after hitting his maiden ODI half-century in only his second match in the format in almost three years.
He was summoned on the eve of the match after first-choice wicketkeeper-batsman Jos Buttler had to have stitches in split webbing on his left hand.
It was a tough mission to replace the brilliant Buttler, who has hit two of the fastest centuries in England’s ODI history - all the more so when the top order failed.
But Bairstow has been in the form of his life for Yorkshire, and took it emphatically into England colours with an unbeaten 83 from 60 balls to see them home with an over to spare.
He could afford a fair dose of personal satisfaction, but made sure to thank England caretaker-coach Paul Farbrace for filling him with confidence to play at his best.
“I’m delighted to have done that today,” said Bairstow, who was dropped on 39 and then 56.
“’Farbs said to me before, ‘It’s your game - just go out and play’.
“It suited me down to the ground and I’m really, really chuffed to see us home.
“I was given a couple of chances, but that’s the game of cricket.”
Bairstow has had an emotional few weeks, during which his maternal grandfather has died.
As he reflected on that, he made mention too of his late father David, who also kept wicket and batted with distinction for Yorkshire and England.
“It was a pretty tough time for us as a family,” he said.
“But we’ve been through it before and it just shows how strong we Bairstows are.
“It’s a trait we’ve had, and I’m sure those of you that have watched my dad play cricket for 20 years will see that. It’s something that runs in the blood.”
Bairstow has had to wait patiently for an opportunity while Buttler has made the position of England wicketkeeper his own in all formats.
He added: “Any time you’re representing your country is pretty good - and other than 10 overs in Ireland I think the last time I played was in (the 2013/14 Sydney Test in) Australia.
“To get the Three Lions back on is fantastic and who knows what’s round the corner?”
England have confirmed Bairstow is added to their squad to face the Kiwis again in Tuesday’s one-off Twenty20 at Old Trafford, with Buttler still out.
But he knows he cannot second-guess when his next chance may come after that.
“That’s completely out of my control, out of my radius, and something I’m not thinking about,” he added.
“I’ve not been thinking about going out for whoever it might be - whether it be Grimsby Town Crusaders during last week, in a charity game, or England this week.
“It was fantastic to pull any shirt on and score runs.
“I’ll go into the next game, wherever it may be, with a lot of confidence and pleased with my batting and also my wicketkeeping.”
Bairstow kept his cool initially in an 80-run sixth-wicket stand with Sam Billings, and then sealed the deal in another half-century partnership - unbroken this time - alongside his fellow Yorkshireman Adil Rashid.
He said: “You’re 45 for five - it’s only human nature to be slightly concerned.
“But at the same time you’ve got two guys at the crease there - myself and Sam - who were well capable of getting us close.
“The guys have put so much work into the series.
“We’ve seen a massive shift and a tremendous series...the amount of hard work and belief that the guys have shown this series is fantastic.
“For me to come into that kind of dressing room (is great), putting a little performance into what has been a huge series.
“It’s something very special and this group of players is very special.
“We’ve got a very long way to go to see how good we can be, but that’s exciting.”
New Zealand captain Brendon McCullum gave credit where due, to Bairstow and England.
“He was very impressive,” said McCullum.
“We’ve seen him play international cricket before and know his pedigree and (that he’s) capable of being dangerous.
“Jos Buttler’s performed brilliantly in both formats, so that was always a loss.
“But Jonny performed brilliantly.”
Eoin Morgan’s team have made a mockery in this series of their miserable early exit from last winter’s World Cup and McCullum believes they can be competitive again at the next one - in this country in 2019.
He added: “I think England’s an exciting group - fast-forward four years, provided they stay true to that style, they’ll be a dangerous team.”