It all depends on the campaign delivery, conversion value and duration
as there should be sufficient data generated, the longer it takes
to generate the data the longer the optimization period. On average
it usually takes 2 months with sufficient data to optimize the campaign
fully to its ROI. Continuous optimization effort is needed after
the campaign has reached its ROI as there are new sources of targeted
traffic dedicated to your campaign each day and to ensure you maintain
a good ROI you would need to review the optimization effort as needed.
