I think that if you manage to go to the gym regulary with that routine until the 16th Dec, you would see the difference by then.
Very true about the testosterone! So if you feel that 10kg is to light, you could bump it up a bit. Starting off slowly is really good. Don't want to pull a mucsle and not be able to work it, when you have made your mindshift, kwim?

Good luck & Congratulations!!