People often attempt to take shortcuts in the execution of premarital agreements. Shortcuts can invalidate the agreement. In California, premarital agreements have to meet certain requirements for them to be considered valid by the court in the event the marriage dissolves and one party seeks to implement the agreement.
The Agreement should be signed at least a week before the marriage; ideally it would be executed much earlier than that. Moreover, each spouse must have had time to read the Agreement and discuss with his or her attorney.
When people come to me to do their Will or Living Trust, one of the questions I ask is whether they have a premarital agreement. It is possible that it will impact the way I draft their Estate Planning documents.