How to prevent double login in time sheet app

I have an app that our users can log times for specific tasks. I have a button on the dashboard that allows users to add a new time record and it returns them to the dashboard once complete.

However, I do not want them to access a new time record if they currently have a time record where they have not previously logged out. I am pretty sure I cannot do this in the current format because I cannot make a formula URL on the dashboard.

How can I insert a check of all of the current records to ensure the user is logged out before I take them to the new time entry page? I need an idea of how this may be accomplished as I am at a stand still to add this functionality in my app.

Thanks,

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Ray Moss
Essence QB Admin
Essence Cabinets Inc.
Edmonton, AB, CAN
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