I do think that the books says that three days is what it takes for the average person to reach ketosis.
Do you have the ketostrips? I use them every once in a while. I can usually tell that I am in ketosis by the way I feel and also my breath would knock over a trucker.
When I check for ketosis I do it first thing in the morning. Sometimes if I chose to do it in the evening I'll get a really light reading because the ketones have not built up in my urine due to the amount of water I have consumed. But you have to remember that not everyone ever achieves ketosis. Don't stress yourself about it. From past experience I know that I will test neg. for ketosis if I've had a good bit of diet sodas for the day. But in all actuality I am really in ketosis because I'm familiar with the feeling that it gives me. One of the benefits of ketosis is the reduction in appetite. Now if I can only learn portion control I'll have this puppy whipped!! LOL!!
My best advice...follow the plan...drink the water...test for ketosis if you want to until you know what it feels like to be in ketosis...a.k.a....tiger breath..appetite is less....and then don't buy anymore of the strips unless you really want to use them
Keep up the good work...your doing just fine. Remember it's one step at a time!
Wanted to add that around the TOM I'm always out of ketosis...I haven't figured out why. I guess that yet another wonderful feature of being a woman.