Your sign up date is important because it determines the invoice periods for your account. If you signed up on the 16th, your invoice periods end the 16th of each month. Therefore, your invoice periods include March-17 to April-16, April-17 to May-16, May-17 to June-16, etc.
As long as you have submitted a payment method and completed tax form, your payment date depends on when the $200 threshold is met. If you meet the threshold in the invoice period ending on April-16, you will receive your payment within 60 days of April-16.
If the $200 threshold is not met in the invoice period ending on April-16, the balance will be rolled over into the invoice period ending on May-16. The balance will roll over into the next invoice period until the payment threshold is met.