General Practice is that, The date of Board Meeting, Notice, Directors' Report, Auditors Report B/s Sheet signing shall be the same.
However, the date of Directors' Report can not be later than the date of Board meeting in which the company approved the notice and annual report because the qualification of auditor, if any, are requied to be explained in the directors report and if there is no qualification it is also requied to be specifically mentioned in the Directors' Report.
It is recommended practice also.
Furthe, it cannot be before the date of that Board Meeting before before that date the Auditors Report is not available so directors report can not be prepared.