Addy borrows $1500 from Belinda. Addy agrees to pay $200 on the first of each month. For the first three months Addys payments are ten days late. Belinda, nevertheless, accepts payment. Addy then pays the fourth payment fifteen days late. Belinda becomes angry and demands full payment of the loan. Addy refuses to pay and claims that the entire debt has been discharged because Belinda waiver the first of the month requirement. Is Addy correct?