I keep my home relatively cool, so the only place I have to bulk is in my oven with the light on. It gets my dough bulking at 82f at the furthest spot from the heat source. At that hot temperature, how long should I be bulking for with a 20% leavin inoculation. I know there are other factors, just looking for a base.
Watch your dough, not your clock. When the dough has doubled in volume, then that is the time.
Ford
If you prefer a little cooler you could try using a smaller wattage light bulb, or put a tiny crack in the oven door. IMO, 78F is a more common temp, but no doubt 82 will work. Your dough will move faster, though.
Maybe tin foil over the oven bulb...
Danny
My room temperature is around 30C (86F), so I bulk at around that temperature. To mitigate that, I autolyse in the fridge. Sometime for a whole night.
I try not to let the dough get too hot. If it gets to 28C (about 84f), I put in the fridge for 30' or so.
I usually bulk for 4h-5h30. I use between 10% and 15% whole wheat flour and also use 20% levain (at 100% hydration).
After that I usually proff in the fridge overnight.
I am still not sure whether I should change this. I have decided to cut my bulk short and instead of 5h+, last time I did it for 4h20. It made virtually no difference.
I'm only a newbie. But I have a colder kitchen and my bulk time was taking forever. So I took some advice from my Tartine Bread book and put a bowl of boiling water in the oven with my dough and it reached a steady 78 - 80 Fahrenheit. Worked a treat for me. :)
20% is higher than I would work with. A nice levain should be able to ferment a loaf at 78 degrees in three hours or less at 12% innoculation. So 20% at 82, I'd say try shaping it and getting it in the fridge at 2hrs 15 min.