Earnings are paid 15th day of next month when they reach $20 threshold.
For example, earnings between 1st of June and 30th of June are paid on 15th of August. If the earnings are below $20 for the given month, they will be added to next month's earnings. For example, a user earns $15 between 1st of June and 30th of June. He won't get paid on 15th of August since it's below $20 threshold. She earns $10 between 1st of July and 31st of July. She'll be paid $25 on 15th of September.