CArdio first thing in the morning works fine.
However, you don't want a completely empty stomach as it your bloodsugar would be too low and besides fat you would burn muscle also , read the following
http://www.cbass.com/Faq2.htm#Training
I should have read this much earlier as I always did the pre-breakfast cardio on a completely empty stomach. Sure I lost weight, but I felt my muscles were getting flat also...
http://www.cbass.com/FATBURN.HTM
First thing to do when you get up is to drink 250 ml water, wait 10 minutes, eat an apple and some BCAA proteine caps, chase them with another 250 ml water, wait 5 minutes, take your ECA stack , warmup for 10 minutes and when the ECA kicks in you do some HIIT on your bike or stairmaster (expensive though them stairmasters to have at home)
After that eat like a pig asap......
Ideally you have a medium sized meal 2.5 hours after that and got to the gym 1.5 hours later as the best time of the day to train seems to be between 12:00 and 16:00 hours for most people.
Can't pull this of on working days, but i like to do it this way on saturday and sunday.