10-12 minutes has worked well for me. 5 min may have more caffeine in it but if you feel ok with it that's great.

I guess I've done CEs long enough that I do not recall the original instructions that I follow but I boil the coffe about 6 minutes and then let cool for hours. I think this is close to what SA Wilson recommends when using their brand of coffee.

As for the numbers 12 to 15, the recommend time to retain the enema 12-15 is based on blood making one lap around the circulatory system every 3 to 4 minutes IE. the blood passing near the colon will be bathed 3 to 4 times.