The rest period between sets is variable according to your goals. For strength rather than muscle size (hypertrophy), longer rests are required—preferably about two minutes or more. For hypertrophy and elements of muscle endurance, shorter rest usually works best—around 45-90 seconds. Considering that this program is designed for a combination of strength and muscle building, you will rest for one minute if possible. Longer rests between sets are sometimes problematic in busy gyms but a longer interval than one minute is fine if that's what you require to continue.
Shorter rest periods have their place — especially if your goal is muscular endurance and fat loss. But longer rest allows you to perform more reps on subsequent sets, and this greater volume, over time, may lead to greater muscle gains in the long run. One convenient way to do this without tacking additional time onto your bodybuilding routine: Perform supersets, which are back-to-back sets of two different exercises that target non-competing muscle groups (e.g., the squat and biceps curl, or the bench press and bent over row).
Aside from that point, weight lifting is said to elevate your metabolism for up to 48 hours after the fact, meaning that not only are you burning calories while lifting, but also for hours and hours afterwards, meaning that the lifting takes sort of a precedence over the cardio, since cardio tend to only burn calories while the cardio is being performed. This is assuming that the cardio is of low to moderate intensity because it is also suggested that very high intensity cardio can cause this same prolonged raised metabolic effect.
After session 12, consider whether you need to increase the weight for any particular exercise. If you can comfortably do more than the RM of 12 exercises, increase the weight by a modest amount, say two pounds or a kilogram for isolation exercise muscles such as triceps and biceps, and 5 pounds or 2.5.kilograms for compound and large muscle group exercises like squats and deadlifts. When using dumbbells, this would apply to each one. Don’t increase the number of sets beyond 3 at this time.