Good day, Raymond. You'll need to run an Invoices and Received Payments Report in QuickBooks Online (QBO). I'll guide you through the steps.
Here's how:
1. Go to Reports.
2. On the search bar, type Invoices and Received Payments Report, then enter.
3. Please choose the correct month/year.
4. For you to see the average days, click Customize.

5. From the dropdown of Rows/Column, click Change columns and please check the necessary option that you want to see in the report.
6. Click Run report.

QBO doesn't have a built-in report for tracking directly the average time for customers to pay their invoices because it mainly provides basic financial reports such as accounts receivable and cash flow. That's why we need to customize the report you pulled up from the steps I've provided.
Please refer to this article to learn the other option to see the average days of each customer: Create an average days to pay report in QuickBooks Online.
After you run the Invoices and Received Payments Report, you can export it to Excel.
Thank you for using QBO, Raymond. By customizing the Invoices and Received Payments Report, you’ll have detailed insights into average payment, helping you manage your receivables more effectively. We appreciate your diligence and are here to support you in streamlining your financial tracking.