I've heard it's best to do it in the morning (before brekky) as it kick-starts your metabolism and your body will buuuurrrrnn through calories for the rest of the day. But, you have to do what works for you and obviously doing 60 mins of exercise throughout the day is better than trying to fit in only 10mins in the morning, itms? I personally like to break my exercise up throughout the day - I get in about 10mins on the treadmill of a morning while the girls are eating breakfast, then I will do blocks of 15 to 45 mins during the day whenever I can find the time. I try to total at least 70 minutes of exercise (I'm a sucker for sugar, if I could cut it out of my diet I'd be less strict on exercising but I can't live without it, so I make up for it in other ways lol) a day, and I generally find that I can get the most done in the evenings when the kids are settled. At that time, I jump on when one of 'my shows' starts and will pound it for 25-min blocks, broken up by light weights and push-ups/sit-ups etc. So that gives me a solid hour if I haven't had a chance to do much during the day, or I can take it easy and do a half hour and then relax and watch the rest of my TV show in peace

Good luck, just keep forcing yourself to do it and you'll soon find a routine that works for your situation and daily routine It certainly doesn't do any harm to exercise at any time of the day - if you're doing it at all, it's a great thing!