Changing the date of next year's early May bank holiday will cost one calendar maker about £200,000, it has said.
Last week, the government announced the bank holiday, set for Monday 4 May, would be switched to Friday 8 May, to mark the 75th anniversary of VE Day.
Allan & Bertram said as a result about 400,000 of its calendars which had already been printed would have to have the May 2020 pages replaced.
The government said it had considered the practical implications of its move.
But the manager of one calendar maker said it had "probably been the single most stressful week that I have ever faced in business".
"We're totally in agreement with changing the date. Just not changing it with 11 months notice, when you've had 74 years to prepare for this event," said Andrew Bennett, managing director of Hertfordshire-based Allan & Bertram.
Bank holiday changed to mark VE Day
It is only the second time the early May bank holiday has been moved - the first was in 1995 to mark the 50th anniversary of VE Day.
On that occasion people were given more notice, said Mr Bennett. "They announced that in December 1993. That was absolutely fine.
"There was no reason why this decision couldn't have been made 18 months ago."https://www.bbc.co.uk/news/business-48631198