If you've made a lot of other changes to your diet, I'd wait at least 30 days before taking on a big challenge. You will be able to tell if your program is working by how much you've lost in that time. If you're losing 1-2 lbs a week and having the pop, then it's all good. If not, you may want to consider some alternatives. Piling on too many new changes all at once is a recipe for disaster in my experience; it gets too overwhelming and I have a tendency to revert back to my last comfortable spot and give up all the changes because one thing was too hard. If I make a few little changes that are easy and one hard change at a time, then wait a bit until I feel comfortable with those changes, I don't get as overwhelmed and if I do give up I have some good habits to fall back to.