Hi Candice - absolutely and perfect amount of time. I would go back to week 9 - 12 and then spend the last 8 weeks focusing on long runs specific to the terrain you are needing to be prepare for.
what race are you doing?
Comrades Marathon in South Africa. I was wanting to do it this year but I have a niggling knee injury. Have decided that after my last planned marathon for this year in August, I will recover and use your Strategic Running Foundation to get me to the finish line, injury free, in June 2015.