What you have done so far looks to be fine (I assume you are using a KitchenAid mixer). Going forward, what will largely govern the success of your efforts is the natural characteristics of your starter culture (some are naturally more active than others), the degree of readiness of your starter (i.e., it is well fed and fully functional), the hydration of your dough (all else being equal, a high hydration dough will ferment faster than a low hydration dough), and the fermentation temperature (i.e., your ambient temperature).
It would not be unusual at the low levels of your starter to not see much volume expansion in your dough for many hours. It can be 12 hours but it might also be 20 hours or more, depending on the particular conditions. Typically, the dough is allowed to ferment in bulk, for example, for 12-15 hours, and then divided, shaped, and allowed to ripen for about another 3-4 hours before using. In a home environment, some people use an inexpensive proofing box (such as described in Ed WoodÃƒÂ¢Ã¢â€šÂ¬Ã¢â€žÂ¢s book, Classic Sourdoughs), or a Peltier unit (such as one made by ThermoKool) to control the fermentation temperatures to achieve more consistent results than relying on room temperature alone, which can vary quite widely throughout the year. It will usually take some experimentation to get things right on a consistent basis. Unless you use your starter frequently, whether it is to make pizza dough or bread dough, you will always be contending with the matter of having to refresh the starter culture (which may have been inactive in the refrigerator for months) to get it back to peak performance levels. That is perhaps the main reason why many people give up on natural starters.
At the level of usage of your starter culture, you should be able to use any unbleached, nonbromated white flour to feed the culture. If you were using a preferment at much higher levels, such as 20-50% of the weight of the formula flour, the type of flour you use might have an effect on the flavor profile of your finished crust. In my case, if I am using, say, Caputo 00 flour, I am likely to use the same flour to feed the starter culture. It is more for authenticity than anything else.
I think you can now see why it is rare to see professional pizza operators use natural starters. It takes a lot of work and starters can be finicky. I am aware of only one pizza operator in the U.S. using a natural starter and only two in Naples. It is far easier to use commercial yeast. In between the use of natural starters and commercial yeast, there are many preferment applications that can contribute to the flavor profile of pizza crusts, such as mentioned, for example, by thincrust in an earlier post in this thread. Aussie member wa dave (Dave) has also mentioned in previous posts a sourdough approach that he uses to get better crust flavors. Tom Lehmann has previously described the use of a preferment to impart greater flavors to a take-and-bake crust. In your case, at the low levels of usage of your starter, you are relying almost solely on the leavening power of the starter. When you get to much larger preferment levels, there are other attributes that are conferred on the dough, such as acid levels, strengthening of the gluten structure, etc. With the growing artisan movement in pizza making, I think you will see greater use of preferments to achieve better crust flavors and textures and also to serve as a differentiator in a highly competitive marketplace.