Before the application is drafted around either one. A file built for an acquisition describes a specific company, its records and its purchase; switching to a startup afterwards means rebuilding most of it. Set a decision date, gather what each option needs until then, and treat that date as the point of no easy return.
Let due diligence set the deadline
The acquisition path has its own clock: an exclusivity period, a financing condition, a closing date. Line the decision date up with the last point at which walking away is still cheap. If the seller's records do not arrive in time to assess them properly, that is a reason to extend or withdraw rather than to proceed on optimism.
Nothing in the immigration process carries a guaranteed decision date, so avoid deal terms that assume one. Set the decision date against the point at which the two files genuinely diverge rather than at the moment a preference forms, because much of the early work serves both options. Nationality, source of funds, the household plan and the general market analysis are common to either route; the business plan, the evidence list and the transaction work are not.
Doing the common work first and dating the divergence keeps the option open for as long as it is cheap, which is what makes an unfavourable due diligence finding survivable rather than expensive.