my opinion is that its important to guage how you feel when you wake up in the morning. some can get by with less, some need more. i get roughly 7 hours sleep and i do fine. i train first thing in the morning so when i wake up, i'm ready to go.
rest and recovery are important in that doing too much will hurt in the long run. HIIT has shown that you dont need to do endless cardio. and hitting the weights for an hour is plenty.
with experience comes knowing when you go to far. for me its easy. when i lose my enthusiasm for training, i know i need a break.
remember, 12 months. not 12 days, not 12 weeks. 12 months, one day at a time. one workout at a time, one rep at a time, one....... ahhh, you get the idea.
you think you're pretty excited now, wait till 12 months from now.