I think i might start mine tomorrow, i have so many reasons why not to start it yet, but will start anyway lol, for unknown number of days, the same as you. I haven't done one before, so even if i last 5 days, it is a start. Might go on to juice for a few days and then back to water, if i find that helps.
You might want someone with previous experience to be your fasting buddy, but will post daily about my experience with it anyway.
I have about 15 pounds to lose, but not doing mine for weight loss really. Eventually want to do longish one for health problems. I'm 5'8", and about 154 pounds.