Some say to prepare your own cranberries.
I cook fresh cranberries for 10 minutes with one cup of water.
Then I pour off the juice into its own glass container, and refrigerate.
...Then sip small amounts.
Stevia, or other preferred sweeteners can be added, but I actually don't need them. I quite like the taste of homemade cranberry juice...though I don't take much at a time.
I don't know the amount or timing that is suggested...although I read that cranberries and plums (prunes) are the only two acidifying fruits.
I just stick to small amounts, occasionally, as a cautionary tactic.
Hope this helps.