Prop 0’s voting window and deadlines depend on the jurisdiction and the specific proposition you’re referring to. At the moment, there isn’t a universally applicable “Prop 0” across all states; several states issue ballot measures with similar naming conventions, and timelines vary by state, county, and election type (general, special, or primary). Here’s how to get a precise answer quickly:

• Identify the state and the exact ballot title or number for Prop 0 you’re asking about.
• Check the official election website for that state (often the Secretary of State or County Clerk/Elections office) for the last day to vote, registration deadlines, and whether same-day registration or provisional ballots apply.
• If it’s a recent or ongoing election, reliable local news outlets can confirm the last day to vote and any relevant deadlines.

If you share the state or link to the Prop 0 you have in mind, I can provide a precise last-day-to-vote date and summarize any important deadlines (registration, ballot return, in-person voting hours) for that specific measure.