Whether you wish to exercise in the early morning or in the evening is absolutely up to you. There is truly no scientific research stating that a person time is better than various other times. It is all up to your personal preferences. Typically most individuals favor training right after school or job, or later on at night. There are truly no problems doing this. One point you can do if you are doing cardio also, is to separate your training up in a morning and also evening part. In the early morning you do your cardiovascular training. Then you return later at night in order to do your weight training.