You may find that you need to offer credit to attract customers.  Consider both how long the credit period should be and how much credit should be offered.  Set limits on how much credit you can offer to any customer at one time to limit your risk form bad debts. 

Seven, 14 or 30 days are common periods of credit.  A good gauge would be the terms that you have been able to negotiate with your own suppliers.   If you offer a longer period of credit you will have a gap between money going out and cash coming in (see the cashflow section).  Can you resource this from your own funds?  Always invoice your customers promptly to start the payment cycle.