WebCrawler, I know the conflict for time and I'm sure the your answer is different than mind. Doing physical exercise is a form of balancing your qi. It it Yang energy and balances against the Yin energy of mental work.
I've had several months off of my physical exercise routine and it was a mistake for me. I'm just starting back at it. However, I often incorporate SFQ into my exercise. If the intensity is not too high, I'll abdomin breathing. I'll open my channels and relax into any resistance work. It really does help.
If I'm sitting on a stationary bike I will go into the emptiness and basically do a meditation. Some I do small universe but usually I do self-concentration. I usually set the bike for a hills or interval type course, but I don't even notice when the resistance levels change. I just have a nice steady cadence and breathing and the time just flies by and finish the ride feeling great; dripping wet but great.
Getting back to your question. There is no wrong time. The better time for the active exercise is the 5 to 7 time frame (morning or evening). Doing it after an exercise is great, if you have the time. Do your cool-down and then into SFQ. You've started your qi flowing with the exercise, just get into the meditation and enjoy.
You are better than I at determining what is the right balance of exercise and SFQ. Learning to find you balance is qigong. 
You are perfection.
Iam2 
