A deadline tells you when a result is needed. It rarely tells you the last moment at which a useful decision can still change that result. Find that earlier moment before the work becomes an emergency.
For a fictional workshop, the room must be confirmed by Friday. Invitations, travel arrangements and printed materials depend on that confirmation. Waiting until Friday to discover the room is unavailable leaves several people with fewer options. The operational question belongs earlier: when must an alternative venue be selected?
Work backwards from the consequence
Name the result, the prerequisite and the realistic alternative. Ask how long switching to that alternative takes. That gives you a decision point, which may be several days before the final deadline.
Tell the person responsible exactly what is needed. A useful request explains the consequence: if the room is not confirmed by Tuesday afternoon, we need to choose between moving the workshop and reducing attendance.
Make uncertainty visible
Record what remains unconfirmed instead of treating silence as approval. Set a review that leaves time to act. If information arrives late, preserve the distinction between what was known and what was assumed.
Use this approach for one commitment today. Identify the latest useful decision, the person who can make it and the fallback you would actually use. The purpose is to preserve options while options still exist. Moving the conversation earlier often matters more than making the reminder louder.