The danger of beginning mind-mapping during an activation layer is the tendency for time to be wasted in drawing the mind-map, and for your mind to be distracted from what you are doing. Each activation session is, after all, only 20-40 minutes.
Having said that, I personally do occasionally mind-map whilst activating, quite effectively. Experiment to see what works for you. If you mind-map during activation, make sure you are aware of your purpose and your questions to bring your focus back.
Another solution I have seen work: Jotting brief reminders down in the margins, or using post-it notes to remind you of insights when you mind-map later.
KWLee
[This message has been edited by KWLee (edited June 15, 2005).]