Invoices are already recorded as income

You can indicate whether each invoice is paid or not. The actual cash flow does not affect your accounting. Suppose you create an invoice in 2022 and the customer does not pay until 2023, that invoice will still be allocated to the 2023 financial year.

Does this help, or what exactly do you mean?

It's confusing for me because I can't see what has actually been received on (a daily 'cash overview', so to speak).

If you look at your dashboard, you will see at the top that your sales invoices are indeed already included in your income. But you will also see a box showing the amount of your invoices that are still open and therefore not yet paid. In the summary of your invoices, you can see the status of each invoice. When your invoices are paid, you can tick this box for the relevant invoice, and this will then be automatically updated on your dashboard.