How do you make an invoice pending?

Hello, peninsulaforklif. 

Currently, we can only marked status on invoice as Open, Overdue, Deposit and Paid. That said, making invoice status as pending is unavailable in QBO.  

We understand that this feature would be a great addition to our product. Having this feature in QuickBooks Online would give it more flexibility and allow it to be more organized. You can send your product feedback by going to Gear icon and selecting Feedback. Our Product Team will review on this for you for consideration. 

As a work around, you may consider creating Estimate. This will enable you to select a pending status. Then once you finalize the transaction, you can apply the estimate to invoice.   

Please refer to this article for more detailed steps: Create and send quotes in QuickBooks Online.

If there's any other help you need aside from changing status of invoice. I'll be around to help you out.