In Illinois, if you want your Prenuptial Agreement to hold up in court, plan it and sign it early. Don't wait until the night of your rehearsal dinner to get it done. In the event of a divorce, antenuptial agreements have been sucessfully challenged if signed too close to the date of the marriage. The reasoning goes something like this: if a prenup was signed too close to the wedding, there wasn't time to seriously contemplate it and the person signing it didn't have much choice in the matter given how soon the marriage was coming up. Other critical considerations when making a pre-nuptial agreement are having your own lawyer and making a full disclosure of finances and assets.