If the relationship is such a good match it will survive a short recess. If the agreement isn't such a great idea your reservations will probably surface more clearly in the shower the next morning. At that point you can either go back and renegotiate or scrap the agreement. Never allow yourself to be rushed into an agreement. If you choose to have the agreement set to paper you might also want to have your respective attorneys look it over.
Lawyers are very good at picking out potential problems in a written agreement.
Use their advice to clarify and strengthen the relationship you are building. However, in small business negotiation it is generally expensive and not necessary to have the attorneys at your side. The presence of a lawyer at the beginning can be often seen as adversarial and you want your relationship to be founded on mutual trust. Finally, remember that just because you start a negotiation doesn't mean you have to finish it. Too often people feel that the initial enthusiasm they have generated for working together means that they should conclude an agreement no matter what.