The recommendations would depend on why you feel you are not presently operating up to full potential.
I would definitely suggest taking a look at Talking to Win, Peak Performance and Instantaneous Personal Magnetism.
If you are doubting your capacities, consider Belief (because what you believe will be substantiated).
With regard to timing and frequency, everyone is different. Pay attention to your results with various approaches until you find what is ideal for you.
Congratulations on taking the big step!!!