Most service businesses never give their clients a deadline for completing onboarding. They send the portal link, the intake form, the document requests, and then wait. And wait. And follow up. And wait some more. The result is onboarding that stretches from five days to five weeks, not because the work is hard but because nobody said when it needed to be done. This article breaks down the three types of onboarding deadlines, how to calculate the right timeline for your service type, exact language for communicating deadlines without sounding pushy, what to do when clients miss them, and a milestone stacking technique that turns one big deadline into a sequence of small wins.