I do this as well, but just with a regular pitcher. I love it! Once a week I cut up some lemons or limes, a chunk of ginger, and some cucumber slices and put in the pitcher, and I have a glass first thing every morning. I just add more water when I get low. I am a hard core coffee person, but since I've been doing this I've found it really wakes me up in the morning (I still have the coffee, just a little later). It's also great for people that have a hard time drinking a lot of plain water. I personally don't think a little lemon will do you any harm on phase I, but if you are following to the letter (and you should, especially if you are new to SB), you can do ginger, cucumber, mint, etc., until you start on phase II. I'm sure there are some good suggestions for non-fruit combinations if you google it.
Life's a journey, not a destination.
It's easier to stay on plan than to get back on plan.