Belfast Chamber has written to the First and deputy First Ministers calling on them to give non-essential retailers sufficient time to allow them to prepare properly for reopening after lockdown ends.
Prime Minister Boris Johnson last night said outdoor markets and car showrooms can reopen from June 1 if they can meet the Covid-19 secure guidelines to protect shoppers and workers.
From June 15 "all other non-essential retail" will be allowed to reopen, contingent on progress in the fight against coronavirus and if the businesses are "covid secure".
The Republic is aiming for June 8 to reopen small retail outlets.
Now the organisation which represents many of Belfast city centre's retailers has asked the Executive to tell retailers when the same might happen here.
Belfast Chamber chief executive Simon Hamilton said: "Non-essential retailers have now been closed for over two months. Easily over 90% of staff have been furloughed.
"We've all seen images on our television screens of once bustling shopping streets in Belfast almost completely empty. Plans have been put in place by many retailers to make their stores safe for staff and customers.
"There is a real keenness to start trading again, but retailers in Northern Ireland are at a disadvantage compared to their counterparts in England and Ireland who both have set indicative timings for the reopening of non-essential retail.
"With the Executive stating that shops can open again at Step 2 on their roadmap, and the indicative dates for England and Ireland just days away, Belfast Chamber believes that it is imperative that the Executive give retailers here sufficient time to prepare for reopening."
The Chamber chief said retailers have done the risk assessments required and developed plans to reopen safely - but it will take a significant amount of time to implement those plans.
He argued local retailers were operating in a vacuum compared to others in the rest of the UK and Ireland.
Retail NI chief executive Glyn Roberts said: "If the Executive give them the green light, retailers who are currently on the 'closed' list can consult and train staff, produce a social distancing plan and retrofit their stores to ensure the safety of shoppers and shop staff by June 15.
"The NI Executive also needs to begin work on a wider reopening plan for our town and city centres, which will ensure the right health and safety guidance for retailers, key businesses, their employees and also consumers.
"It is vital that we create confidence in shoppers that our high streets will be safe in the event of a wider reopening plan."