In order to be enforceable, a prospective spouse must be given at least seven days to review a prenuptial agreement before signing. This gives the prospective spouse time to seek legal advice and review the agreement.
It is better practice to allow more time whenever possible, as it is not always possible to get in to see a family law attorney within seven days, and more time may be needed if changes are requested.
Do not wait until the last minute to present a prenuptial agreement to your prospective spouse.