If I'm adding the levain to the flour and water before autolyse, what is the maximum time I can autolyse for? What about if I keep the dough in the fridge?
rest of the flour, then you are no longer doing an "autolyse" --- you are starting the fermenting process. The "autolyse" is supposed to be strictly flour and water with no added source of yeast (whether the levain or a poolish or straight commercial yeast). The purpose is to hydrate the flour and allowing the beginnings of gluten development without fermentation.
Some folks do a long autolyse at room temperature (starting with cold water and chilling the autolyse), and so add the salt to it to prevent any fermentation starting from the natural yeasts existing on the flour (they don't want to create a new starter!). Most, however, find that 1 to 2 hours of autolyse at room temperature is sufficient to hydrate the flour and make it faster and easier to develop the gluten, and so either don't add the salt until the add the levain, or just add the salt on top and don't mix it in until they add the levain.
What you are doing is actually the final dough mix, including the flour, water, salt, and levain. Once the levain hits the flour, then the timing is going to be determined by the ratio of prefermented flour to total flour, the dough temperature, the ambient temperature (room or fridge), the overall size of the dough, and the amount of active yeast exist in your levain. I find that the table created and referenced in this thread is invaluable for figuring out a ball-park schedule: http://www.thefreshloaf.com/node/5381/sourdough-rise-time-table
Hopefully this helps!
if the OP isn't adding the salt to the starter, flour and water until later, he/she isn't mixing the final dough at that stage.
IceDemeter is spot on. This is not an autolyse. Established leavain/starter added to flour equals fermentation. No escaping that fact. The whole point of an autolyse is to allow native enzymes to do their thing. Once you add starter/leavain it's a whole different kettle of fish... pH is altered and enzymes have an optimum. In another respect there is a matter of oxidative state.
A (the purposefulness of a) true autolyse will ever only be raw flour and water. It's the whole point!
To the OP: retarding immediately will be fine. At least for a couple of days..
Guess I could have been clearer. I wasn't trying to say that adding starter to the flour and water was an autolyse, but rather that without salt, it wasn't a final dough, which is what it was called in the reply to which I replied.
Autolyse does not have a big effect on the final product, especially if you are not baking 100% whole grains. I have baked with and without autolysing and I can't tell the difference. I have had good consistency without autolysing.
Stretches and folds are in my opinion the most important thing in the bulk fermentation. It makes the dough so silky and helps gluten formation.
In his book, Hamelman notes that while real autolyse technique does not involve the addition of yeast, exceptions are made when very wet levains are used. His classic sourdough recipe uses a 125% levain, a quick mix just to get things hydrated and a autolyse prior to the addition of salt. This is the technique that I've been using.
I purists don't want to use the term autolyse that's fine with me. :-)