You have to find what works for you..
I have read a couple things that I tend to follow, however....
Exercise first thing in the morning BEFORE you eat. This allows you to do a couple of things, first, you burn off stored energy having fasted for a number of hours. Second, it kick starts your metabolism for the day, and you will get benefits of a slightly better caloric burn throughout the day as a result. Third, when you eat your perfectly balanced Nutrisystem breakfast AFTER the exercise, your body will properly store the energy for later use in your muscles rather than as fat because you will have depleted your glycogen stores..
Exercise at night is not bad...but some people react poorly to late in the day exercise. Your metabolism will ramp up, as will your brain...in other words, you become more alert and your body may not want to go to sleep..
I, however, tend to exercise whenever I can fit it into my schedule and have not suffered from that pattern. I try for the morning and if I fail I shoot for the early afternoon...last chance workout at night. I know some people do 2 a days...the sheer fatigue overcomes the extra alert boost at night..
The number 1 rule is ALWAYS to do what works for you. If you enjoy it, you feel good about it, and it isn't hard to fit in your schedule, then you are more likely to keep doing it!!!!..
It varies for people..
I can not eat before exercise if I do I feel sick. I would definitely say if you are doing anything outside do it early before 11am as it gets too hot by mid day, OR wait till evening..
Depending on your current fitness start slow and build upon your starting point. The plan will only works better with exercise..
Do whatever you enjoy and stick with it and you will do great...
My philosophy, based on experience and some research, is that if you are going to exercise in the morning, then do it before eating and pretty much upon waking. Otherwise, you will get too hungry and not have the adequate energy to complete a workout. If you can't wait to eat breakfast then you need to allow yourself AT LEAST an hour (up to 3 hours) BEFORE you exercise..
Eat within 30 minutes of completing you exercise. Like cautiously_wary stated, your Nutrisystem breakfast is great for refueling and will protect your body, allowing it to 'heal'. If it turns out that you need to exercise after you eat (within a couple of hours of eating that it) or at some other time during the day, I recommend that you 'save' one of your snacks...preferably a protein snack like greek yogurt, for after your workout. Again, make sure you eat it within about 30 minutes..
As stated above, workout when you want...as long as you are moving, you are doing great!.
I prefer to eat my Nutrisystem entree and fruit before working out. Then, after I shower and get ready for work, I eat my protein serving..