The survey of members of the Night Time Industries Association (NTIA) revealed that 95% of businesses had already made financial commitments and preparations for a 21 June reopening.
It comes as ministers have said it is “too early” to tell if it will be possible to reopen nightclubs next month.
If the country is allowed to progress to the final step of the Government's unlocking roadmap, all legal limits on social contact would be removed and closed businesses allowed to reopen from 21 June.
However, there are concerns about a coronavirus variant first identified in India, which has been found to be more transmissible than previous dominant strains.
Ministers will look at Covid-19 data including on the Indian variant of the virus ahead of an announcement about the future of the roadmap on 14 June.
The NTIA has warned that any delays or adaptations to the roadmap could spell business failures and job losses.
NTIA boss Michael Kill said: “The stark reality for both the industry and for Government is that thousands of businesses risk being plunged into further financial hardship by a deviation from the reopening plan."
Just under three quarters of businesses surveyed (73%) had called in staff while 54% had ordered strock and 60% had sold tickets.
What’s more, 85% of operators require at least a fortnight’s notice to get ready for a relaunch while over one third said they would need at least four weeks to prepare.
Kill added:“Evidently, the Government has a misguided understanding of the timelines, preparation and operational requirements of our sector, given the ridiculous seven-day notice period they have said they will give ahead of reopening."
Overburdened with debt
"Operators have asked for a minimum of three weeks to prepare for opening and, as with the events sector, have been forced to take financial risks by investing in preparation for opening, including by needing to recruit staff amid shortages, procure equipment and perform maintenance on their premises.
“Ultimately, the inability to plan could cost operators dearly if we see the date for a full reopening slide."
Night time economy adviser for Greater Manchester, Sacha Lord, called on the Government to “stand strong and allow some of the hardest hit industries to prepare for opening with some level of confidence that there will be no further delays”
He added: “These businesses are already overburdened with debt, struggling to rebuild the workforce and under pressure to prepare for opening in an extremely short period of time. Let’s not make things harder by moving the goal posts.”