When should I get my first check?

I was approved for Soc. Sec. Disibilty last month (Nov. 2008), the Soc. Sec. office told me I would get a check this month (Dec.). Here it is Dec. 15 and I have not gotten even a letter yet. I really need to know when I can expect a check, the bill collectors are driving me crazy! It has been almost 8 years since I first filled!