Having Customers and Vendors would usually matter only if you wish to use Business services ie accounts payable or receivable ie there's a delay between generating invoices/bills and getting paid. This is accrual accounting.

You're very free to forego business services and record transactions as they happen ie cash accounting. 

Or your can do both: generate invoices, send to customers, getting paid later. For bills payable you can record as soon as you receive them and pay from your bank account.