I've got you covered, Dominic. We can add new Preferred invoice terms in the Account and settings to specify the days for payment from the invoice date. I'd be glad to help you achieve this in QuickBooks Solopreneur.
Here’s how you can do it:
- Navigate to the Gear icon, then Account and settings.
- Go to Sales tab and click the Edit icon in the Sales form content section.
- In the Preferred invoice terms dropdown, click + Add new.
- Provide a name for the new term.
- Select the radio button for Due in a fixed number of days and enter “1” in the corresponding box. This will set the payment term to 1 day after the invoice date.
- Once settled, hit Save, then Done.

Alternatively, you can choose the Due on receipt option, which requires payment to be made immediately upon receipt of the invoice.
Once you've set this up, please return to your invoices and select the new term you just added (set to 1 day). Then, complete the remaining details of your invoices before sending them out.

Once your customers pay their invoices, let's document it using the Record payment feature in QuickBooks. This ensures the invoice is marked as paid.
Please let me know if you have further questions about your invoices, including customizing default emails or recording payments in QuickBooks. We, in the Community, are always here to help!