Hi ozzie. The duration, type and timing of SFQ practice all follow the good, better, best model. Master Lin gives us the best practices to follow, but doing any is good.
First a shower is the same as a bath.
If you can do SFQ meditation, that is good. If you can wait 10 minutes before showering that is better. Waiting a half hour is best. I personally plan on 20 minutes for morning active exercise, but sometimes it's only 10 minutes.
The idea is that the longer you wait after the exercise the longer the flow of qi that you setup in your meditations will last. The 30 minutes is probably related to the time for a complete cycle of qi in your body.
You can mix your time for active and sitting meditations. Probably best to do the active first. Work on your yang then your yin. Clear your system then build capacity.
Also the 5:00 - 7:00 (am and pm) windows are the best time for active meditations, but it's good to do them at any time you have available. Same hold for the noon and midnight periods for sitting meditations.
You are perfection.
Iam2 