After more than three years of controversy, a decision on the Heathcote Hall development is expected to be made next month.
The development proposal includes restoration of the historic mansion, construction of 35 townhouses and 20 apartments and extensive landscaping.
Sydney South Planning Panel has scheduled a public determination meeting for August 21 at 2pm in the Sutherland Shire Council administration building.
In June last year, the panel deferred a decision until more information was provided.
In May, Residents Against Over Development spokesman Phil Smith said it was expected that, with the state election out of the way, the development application would be "rubber stamped".
"How this proposal can be given the go-ahead in a residential street next to the Royal National Park is beyond us,' Mr Smith said.
"It is massive over-development for a developer, state government and council who have no regard for its local community who have one entrance and exit over a tiny bridge and one which is surrounded on three sides by the Royal National Park."
The August 21 meeting is expected to draw a large number of residents opposed to the plans.
The panel will hear final submissions from the developer and residents before making a decision.
The project has been scaled back in size since initial plans were released to a public outcry in April, 2016.
However, there have been only minor changes to the development application, which was lodged in April, 2017.