Flyfisher's suggestion is good. Here is another suggestion:
Create a separate invoice for each of the service date, and generate a 'customer statement'. Customer statement can be generated as following:
- Go to 'View' -> 'Customers',
- In the customers list window, select the desired customer, right-click on it and select 'Statement'
- It lets you preview, print, email and save the statement.
If you view the statement, you can see that the first column is date column for each of the invoices.