It depends on how many peaks you require for your athelete. Pro players would mostly try to peak four times per year in respect of the grand slams but may change according to their personal goals for the year. In respect of good junior players I would probably go for a double or triple peak, with key events spread around easter and the summer or easter, sumer and end of season.
So you'd be looking at about 6-8 Weeks Preparation, 4-6 weeks specific prep, 2-3 weeks competition, 1-2 weeks active rest. Depending on how your players peaks fit into the calendar - if they're on a double peak then they could go longer in each period.
The other thing to consider is the Volume and Intensity of training at each phase for the four performance factors, for example in the Prep phase the Technical volume is high (as this phase is where you make your technical improvements) and the intensity is lower. As you move through Spec-prep to Comp the volume lowers and the intensity rises to match competition levels.
Have a look at the planner below which I produced for one of my players a few years ago - should give a rough idea on how to get going. This part shows the first 2 peaks of a multiple peak year.
If you need any more help drop me a line.