I like to pick peas when the pods are full and round and the peas are plump and sweet.
Peas in the pod will keep, unshelled, for a week or two in the fridge. So if something happens and you can't get to them right away they can wait for you until you're ready.
I shell them in batches if I have more than I can get done in about an hour.
After popping the peas out of their pods and rinsing them I put a pot of water on the stove and I set up a bowl of ice water in the sink.
When the water on the stove is boiling I dump the peas in there and begin to count, "one thousand one, one thousand two..."
After 90 seconds I drain the peas and dump them in the ice water just until they are cooled.
Then I pat them dry with a towel and vacuum pack them for long term storage in the freezer.