How can I recognize revenue after the month that I want the sales to be recorded in? Please help!

Summary

I have to recognize revenue of a PPM contract-line project after the final day of the month but it has to be recorded as the sales of the previous month.

Content

For instance, the situation is like this:
- A sales event dated 31th July, 2020 and this has to be recorded as sales in July.
- The revenue recording procedure must be taken in the first week of August. This is the fastest  timing that I can get to operate.
- So, I thought about leaving the accounting period of July open. But the vendor said this keep opening accounting period won't allow me to record sales of July with the August operating.