As far as preparation for the fast, I don't know of any special preparation. The book will request to take the laxative tea the night before the fast. So practically, you begin the fast at night...
Saying that, maybe because of the reaction to the salt flush, you'd rather try to eat as little as possible prior to the fast. It may make the 1st day or two easier (?)
Blood Sugar level:
Hmmm... I don't think it's a problem. If you feel you need more sugar, simply -drink- the maple on its own. I believe you can safely take even couple of ounces of maple 'as is'. As the maple is the sweetener with the lowest glycemic value, you should be just fine.