Yes, it is. You do want to ensure that the seller is the proper party to sell the condominium to you and that the property is in order, don't you? What if, for example, the seller isn't really the owner? Sure you can insist on signing the SPA first. If the documents later reveal some discrepancy, you'd be facing a whole lot more trouble than just not having a new place to move into after getting married. Don't be hasty and put pen to paper without having everything verified first. Backkom gave good advice - set a deadline. If it's not adhered to, move on.