If this is to remind on approvals, there is a system setting to send out mail reminders to those that have to action on approvals (unfortunately not configurable when to be send out).

In our company we have direct managers or project managers to approve timesheets depending on project setup.
What we do is populate specific user group if timesheets are pending for approval and then run a schedule WFR to send mail reminder to everyone in that group.

Hi there, thanks for your input! Our direct managers are looking for a notification when a timesheet is submitted. Often times timesheets need to be corrected so they’d like to be notified when it’s submitted. 

Hi Kayla

You would need to create a workflow on Timesheet that meets the conditions that State has changed and State is now = submitted (IsChanged($State) && $State='Submitted') to then send out a discussion post or send email to the submitter’s direct manager.

I hope that helps you with configuring this to your liking.