Thanks for contacting the Community for support. I'm here to help you out with setting up a timesheet approval process.
You may want to check out an app that integrates with QuickBooks Online that will get the job done for you. One that's popular among QBO users is another Intuit product called TSheets. According to the overview, "Your employees can track time from any location, using any device. Time data automatically syncs to your QuickBooks account in real time. From there, you can edit, review, and approve employee timesheets for payroll, job costing, billing, or invoicing — all without ever leaving QuickBooks!" You can read more information about TSheets here: https://apps.intuit.com/tsheets.