I recommend at least 8 to 10 weeks of running-specific strength training under your belt before you incorporate plyometrics. Furthermore, it is essential that you practice good form when implementing plyometric exercises. Performing them incorrectly can increase injury risk significantly.
Following the hard days hard, easy days easy principle, your plyometric workouts should come after your hard workout days. Complete plyometrics only once per week, and use other strength training days for core, hip and injury-prevention work. Try these seven plyometric exercises to boost power and improve running economy.