I usually wait a couple of hours between acid additions to my IG pool, just to give things time to circulate well--and that's after I've added it into the return stream, which helps circulate it a little faster. Baking soda and borax go slowly into my skimmer, and I usually jut wait the 2 hours as a rule of thumb.

As far as amounts go, in my 29K gallon pool, each cup of muriatic acid decreases my pH by about .1, and my TA stays around 100.(The higher the TA, the more acid required to move the pH by the same amount, so if your TA is high, it will take more). In a 15K gallon pool, I'd start with 1/2 cup increments and adjust as necessary. It won't take but a couple of additions before you get a feel for the amounts needed for your pool. I'd also start with a cup or so at a time of the borax/baking soda until you get an idea of how high you're wanting to raise it and what amount it's going to take for your pool. Just remember it's always better to "sneak up" on your target number instead of adding a bunch at once and overshooting it!

Janet