What you're describing is a time-lock puzzle (https://en.wikipedia.org/wiki/Time-lock_puzzle https://en.wikipedia.org/wiki/Time-lock_puzzle) and there are ways

What you're describing is a time-lock puzzle (https://en.wikipedia.org/wiki/Time-lock_puzzle https://en.wikipedia.org/wiki/Time-lock_puzzle) and there are ways to do it but none of them are perfect