Four months and seven days (129 days) have gone by without repayment.
I compound the amount owed daily, but at a rate as if it was compounded monthly. The formula I use is:
31*((1.09^(12/365))^[number of days since 4 August 2012])
As of 11 December 2012, KingKatari owes me 44.67772601 BTC. (This can be paid in USD, as per the original agreement.)