Cooler temperatures = longer fermentation time. I write down my start / stop / total fermentation time and rate the outcome on the back of an envelope. I have my last 72 batches recorded - so I can look back to various seasons and see how long a good batch took.

I've been fermenting for 19 hours for 5 star batches - but in my learning curve I've found that I have to look at the bottom of the gallon ball jar and as soon as I see a bubble I know it's time to harvest ( shake, strain, pour / mix ( chia seeds, cocoa powder, instant coffee )into individual coffee cups ).

Normal has been around 19 hours, and the batch before last didn't show the bubble but I harvested anyway and it was runny (still good to eat though!). The last batch took 26 hours plus before the bubble showed - 5 star batch!