That highly depends on the role and the level of marketing that the hiring company has invested in or conducted, but the first referrals tend to tick in within a few days, but for some roles, it may take longer.
In our experience, referrals keep ticking in weeks or months after a Job Posting has been published, so Vouch is also ideally suited for roles you are "always" hiring for.
Vouch has several built-in processes to nudge candidates to review the opportunity they are vouched for and quickly accept or reject it.