The boss of a not-for-profit social enterprise plans to reopen 19 leisure and fitness centres on 3 December, the day after lockdown in England ends.
But Warren Smyth warned there will be problems if the government changes the rules at short notice.
"If we get a change of tack the day before, the impact on business and customer confidence will be significant," he said.
The British Chambers of Commerce (BCC) has called on the government to give a week's notice of any new restrictions that may apply when the shutdown ends.
The organisation - which represents more than 70,000 firms employing six million people - said the government must give businesses adequate time to prepare to reopen.
"Nine months into the pandemic, business communities are still crying out for timely information and a clear strategy from government so that they can survive and rebuild," said BCC director general Adam Marshall.
"Delays and imprecision mean people lose their livelihoods."
The lockdown in England will run from 5 November to 2 December, but Cabinet Minister Michael Gove warned it could last longer if infection rates do not fall.
Meanwhile, ministers are reviewing the tier-system that was in place before the shutdown amid suggestions that the rules may change.
"We have worked hard to support our customers to keep healthy and active which is even more important than ever this year," said Mr Smyth, who employs 600 people at Abbeycroft Leisure in Suffolk.
"We need clarity and a plan to help with our recovery and the future health of both our communities and our businesses."
Kym Morris and Sian Jaoko, co-directors of Earth Florists in the Wirral, are worried about whether they can reopen in time for the crucial Christmas period.
The business would need to order extra flowers a week before opening the shop again to make sure they have them in stock, but they are not yet sure if they can reopen on 3 December.
"Christmas is the busiest time of the year for florists," Kym said. "Opening on 3 December is a really important opportunity for us to claw back some of the revenue we've lost."
If they have to delay their reopening they fear customers will buy their seasonal wreaths from larger stores that have continued trading.
The BCC has asked government to explain why businesses in sectors such as leisure, non-essential retail and beauty have been forced to close despite their efforts to comply with Covid-secure guidance.
"Businesses have played their part by working hard and spending hundreds of millions of pounds to become Covid-secure, in line with official guidance," said Mr Marshall.
"We must see the evidence for why many were forced to close again on 5 November, and absolute transparency on what may happen from 2 December."