Many start as early as six weeks before the target peak, but I feel three weeks before competition is perfect. Be sure to avoid pushing yourself too hard in most of the sessions. You have to leave some surplus energy in your body. This is where you lay the foundation for your performance peak.
Do volume training, strength workouts, but also intensive sessions. Focus on nutrition and be sure to get enough sleep to help your body absorb the training and hold onto the surplus.
The last few days before an important competition, I tend to do a few hard sessions, as icing on the cake. This is where you go over the technical details of your skiing.Leave your body wanting more after each training session. I enjoy several short sessions, rather than few long ones.
Don’t worry too much about missing the peak. Performance comes with the surplus of energy you’ve been building up. It is always hard to know exactly when you hit your peak, but searching too much for the answer, and repeatedly testing your current status, can ruin that moment where you really need your surplus.