I didn't really notice until I went to 1 bottle per day (unfortunately for price). I would say work up to 1 bottle, and give it at least a couple weeks. If you aren't noticing a difference by then, then maybe probiotics aren't going to be helpful.
I actually tried to make a deal with my HFS last time I went LOL. I said I'd be buying two cases per month, and can I get a discount? She sorta laughed but then realised I was serious and went to get the manager. The manager had left so next time I'll try again. I wish I could find a HFS with a sort of 'member' deal where you can build up points to use towards products. Ah well..