Usually, an Air Still wash takes approximately 7-10 days.
This is greatly affected by the ambient temperature, so be sure to store the wash, out of direct sunlight at around 18°C-24°C (64°F-75°F).
To determine if it is complete, check the SG (specific gravity) (this reading is taken with a hydrometer) has been stable for 2 consecutive days, you are aiming for an SG reading of 0.990 for the best results.