In Baker v. Brannen Goddard Co., 274 Ga. 745, 748 (2) (559 SE2d 450) (2002), the Supreme Court of Georgia held that a contract obligating a defendant to pay commissions for the plaintiffs' procurement of a tenant was not entire "because the contractual consideration at issue is not a single sum certain which remained unpaid after a definite due date." Id. at 748. Rather, and because the defendant was required to pay the commission on a monthly basis, the statute of limitation began to run at the time each payment was due. Id. at 749.