The Queensferry Crossing will now close for six days just 48 hours after opening next week, Transport Scotland has announced.
The £1.35 billion bridge is expected to open in the early hours of Wednesday 30 August but then close again early on Friday 1 September for preparations for 50,000 people to walk across over the following two days.
The 1.7-mile-long crossing will stay closed for the Queen to officially mark its opening on Monday 4 September - the 53rd anniversary of her opening the adjacent Forth Road Bridge - followed by bridge walks for local people the next day and clear-up work on Wednesday 6 September.
Previous announcements had not made clear the bridge would be closed to traffic on 1 September, and had stated it would re-open on 6 September.
On 30 August, all traffic except pedestrians and cycles will be switched from the Forth Road Bridge to the Queensferry Crossing.
Then on 1 September, they will be transferred back to the Forth Road Bridge.
After the Queensferry Crossing re-opens on 7 September, the Forth Road Bridge will remain open to only cyclists and pedestrians, on their existing segregated paths.
This is to enable road links to be completed at either end of the bridge, to be completed by early November.
After that, buses and taxis will use the Forth Road Bridge in its new role as a "public transport corridor".
The Queensferry Crossing will then become a motorway, with its speed limit raised from the temporary 40mph when it opens to 70mph.
The IAM RoadSmart motoring group's policy and research director Neil Greig said: “It all sounds a bit confusing for drivers trying to plan their journeys, but the opening arrangements for a project of this size in Scotland is in many ways uncharted territory.
"The key issue is the Queensferry Crossing must be safe when it finally becomes operational.
"We would encourage private and commercial drivers to visit the dedicated websites and check the latest traffic information to make sure they know what is happening ahead of them.
"After the obligatory opening celebrations, the true test for the bridge will be how it delivers on its promise to provide smooth and consistent all-weather journeys for the thousands who will use it in the coming decades.”
Buckingham Palace has confirmed the Duke of Edinburgh will accompany the Queen on 4 September, as The Scotsman revealed on 5 August.
It will be his first official appearance since retiring from public engagements three weeks ago.
Palace officials had said then that he may accompany the monarch at events from time.
First Minister Nicola Sturgeon will also attend 4 September ceremonies at both ends of the bridge along with construction workers, with a blessing by the Moderator of the General Assembly of the Church of Scotland.