The BEST, in my opinion, if fat loss is your goal, is to do cardio first thing in the morning 5 days per week on an empty stomach. Then weight train 3x per week in the afternoon/evening.

If AM cardio is not an option, do cardio after your weight training on weight days, and then whenever it is convenient for you on the other days (non-weights days).

You do not HAVE to do them in the same session.