Teresa,
I think you should be OK in your case, especially since you are also using commercial yeast. It doesn't take much commercial yeast to make a quality dough as long as you allow a long enough period of time for the dough to develop.
It's impossible to forget the flour and water, but it is possible to forget the yeast, salt or oil. At some point you would discover that you forgot to add yeast, but that wouldn't be fatal since the dough otherwise is just a mixture of flour and water and will just sit there doing nothing except hydrating. Such a dough will have a texture and look more like putty and will have no springback whatsoever, at any time, when you push your finger into it. That will usually make you ponder whether you forgot the yeast and, if so, you can recover from the omission by just hydrating the "missing" yeast (even IDY) in a little bit of water and working it into the dough.
Salt may be the ingredient that is most forgotten, especially if you are using an autolyse where the salt goes in at the end of kneading rather than at the beginning, which is far more common and makes forgetting less likely. Unfortunately, the only giveaway that you have forgotten the salt is that the dough will rise quite a bit higher without the salt. But you might credit the yeast for that. Worst case is that your crust will have poor taste and you will have to rely on adding salt to the finished pizza. You will still detect the lack of salt in the crust, and the crumb and crust may be different from one with salt, but at least the pizza will be salvageable.
If your dough recipe calls for oil, forgetting it will also not be a disaster. You can always coat the dough with the "missing" oil during rising or retardation or even when you are ready to shape it into a skin. It will ultimately get worked into the dough--either during a punchdown or when you start to shape it. This may not be as good as working the oil in the dough at the outset (to better coat the gluten strands and achieve better extensibility) but you will at least get the flavor and coloration effects of the oil upon baking.
I'll be interested in the results you achieve from adding the preferment a bit later in the sequence. But don't be surprised if you don't detect a lot of sourdough flavor. Maybe your preferment is more potent than mine, but I have discovered that when I combine both commercial yeast and a preferment, the flavor contributions from the preferment are noticeably reduced. Many people combine commercial yeast with a preferment as a belt and suspenders approach, often because they don't entirely trust their preferments to do the whole job.
Peter
