Yes, you can add shifts manually (and on a future date) directly from the management dashboard.
To add a shift manually, sign in to your dashboard. Go to the Manage Shifts tab and click the "Add New Shift" button on the navigation bar.
Once you do this, you will be prompted to select a date and add information about the shift. You can even deduct a break from the total shift time if you would like. This is what it looks like when adding a new shift manually:
After you are done adding all necessary information about the shift, select Save. You will then be able to Approve this shift as you would any other. After the shift is approved it will show up on both billing and payroll reports.