Payment is typically collected when the agreement is signed.Depending upon the payment terms (which should be defined in the contract) payment may be due on receipt of the invoice, net 30 days or even net 60 days if the customer is a large enterprise.Payment may be made in full (in advance), or in payment increments of monthly (especially for recurring/SaaS vendors), or installments based on progress. This should also be defined in the contract, along with payment default implications.