When you schedule your training is completely up to you.
Timing is secondary to training consistently and achieving your calorie deficit consistently. In a perfect scenario, there are advantages of doing cardio and weight training in separate sessions or at least doing cardio after weights in the same session.
Research at the University of Victoria in British Columbia found that weight-lifting performance suffered right after doing intense cardio and up to eight hours afterward, especially for the legs.
It’s tough to do cardio after an intense leg workout and even tougher to do a leg workout after intense cardio.
If you separate cardio and weights, fatigue won’t get in the way as much. The fresher you are at the start of each workout, the stronger you’ll be and the harder you can train.
Sometimes, however, what’s optimal on paper is trumped by personal preference and practical considerations.
Many people feel fine doing cardio right after weights, not to mention that schlepping to the gym twice is inconvenient.
So if you do cardio and weights in the same session, which should come first?
The answer is: whichever is the higher priority. When the goal is to burn fat and maintain muscle, weight training goes first and cardio second.