The epicarp should be removed within 24 hours after the nut comes off the tree. If left on longer it will start to stain the hard, inner shell. If you cannot find the time to remove the epicarp within 24 hours, you can stretch the time needed by keeping the unhulled nuts under refrigeration.
The hull can be peeled off by hand or can be removed by abrasive action. Small growers commonly use an old commercial potato peeler that can rub the epicarp off. Some growers put the nuts in a sack and roll it around with their feet..dump the nuts and loose epicarp out on a table and sort the nuts from the hulls.
After removing the epicarp, the nuts should be rinsed quickly in cold, clean water. Remove the nuts from the water and dry. A drying table can easily be made.
Make a box using 1x6’s for the sides, and screen for the bottom. A lid can be made by 1x4’s for the sides and clear plastic for the top. The box can be set on saw horses (it needs to be up so the air can circulate). The nuts can be put 3” to 4” deep in the box, stirring them in the morning and evening. Usually, they dry in 3 to 4 days this way and the flavor is delicious. A 4x8 drying box will hold about 300 pounds of pistachios.