The framework's own stages are fee, vetting and then payment, and vetting is the stage without a reliable published duration. Because it also operates through the existing first and second employment-based preference classifications, ordinary immigrant visa processing and any applicable waiting times apply after it, so no start date should be promised on the strength of the payment alone.
Do not let a start date be built on an unpublished timetable
Employers plan around dates, and this framework does not reliably supply one. Vetting takes as long as it takes, and the classification stages that follow are the ordinary ones, with the queues and procedures they normally carry. Hypothetical example: an American company tells a designer from Sainte-Cécile-de-Milton that it needs him in place for a product launch in six months and proposes that he begin work while matters are processed.
Beginning work in the United States without an authorising status is not a shortcut; it is a violation with consequences that follow him through every later application. If the company genuinely needs him sooner, the honest conversation is about whether some other classification fits the immediate need, with this framework running in parallel on its own timetable rather than as a promise about the calendar.