tips for white belt/too old to compete?

I'm 35 years old, no martial arts background and am just starting judo with the goal of eventually competing when sensei feels i'm ready. Being 35 i feel i need to make up for the wasted years of my youth lol and am jumping wholeheartedly into training. I lift at the gym 3x a week, train at the dojo 3x a week, run 3 miles 1x a week and consider myself to have athletic ability, although i am aware of my weaknesses and areas that need work. I know there is very little judo training i can do independently at home and my question to all the experienced judoka here is this:

looking back on your training, what would you do differently as white belt to really make your training process effective?

Second question: At 35, am i too old to compete?

Thanks guys, appreciate the advice