Keep in mind whether your industry is one where you invoice upfront before any work has been completed. In this case you'll be detailing the progress of the project as opposed to doing a monthly invoice.
Terms (or Payment Terms): Invoice terms depend on common practices of your industry, your relationship with the customer, and your cash flow needs. For example, “Net 30” means that the invoice is due 30 days after the Invoice Date. Be mindful some businesses may pay later than the stated due date, so you may want to include a buffer to keep your business free from a cash flow gap.