My husband turned 66 in Oct 2018 and applied for his SS. I am turning 66 Dec. 3 2018 . SS gave me a Dec 31 apointment you me to apply for spousal benefits. . Will I get the 2.8% cost of living increase the next day added to what ever amount they tell me I am getting on Dec. 31 ? Is there any benefit in waiting until Jan 2 2019 to apply ?