Billowy v. Overfermented
Today I began Field Blend #2 (from Forkish's FWSY). Kitchen temp was a nice 74 F, and dough temp after initial mixing was 78 F. I included the instant yeast along with my levain and kept an eye on the dough (as so often advised and after naively following Forkish's lengthy bulk fermentation time estimate with a previous bake). Four S&F sessions spaced through the first two-plus hours tightened up the dough, and then I let the process continue. After a little under four hours I had a nice billowy dough, which I then divided, pre-shaped, paused for a bench rest, final shaped, put into bannetons, and then put into the refrigerator (where the loaves now sit for baking tomorrow).
Baking from FWSY has definitely forced me to pay attention to time and temperature, but as a newbie I also lack the experience to recognize signs that others who post here would notice. Watching the dough rise got me thinking about the aim to achieve billowy dough versus the aim to avoid overfermenting.
What are the things the rest of you look for in sensing that your dough is not yet overfermented? The finger (or poke) test works nicely for proofing, but is there an equivalent for the bulk fermentation? Is billowy the point at which to divide and pre-shape? In Tartine, Chad Robertson writes about looking for a cohesive mass, bubbles on the side of the container, ridges that hold their shape a bit after a S&F (among other things).
Thanks for any helpful hints.