Depending on your business process you can decide how you would like to create expenses and how they flow through the approval process. There are two options to choose.
With this option expenses are created separate from the timesheet. Meaning expenses are a separate page where you create expenses and they can be created anytime. When expenses are submitted for approval the approver is approving the expenses only. Also an advantage of this option is it allows you to group expense items under the expense. So if you are not sure which way to go this is the recommended choice.
With this option expenses are created while you are adding time to your timesheet. Meaning expenses are added for the same week of your timesheet. And the expenses are submitted and approved with the timesheet.With this option you are constrained to having expenses added in a timely manner as it follows the same week of your timesheet.
To set which option to use visit the following page in the setup area.