How do you enter purchases from before starting as a self-employed person?

I have additional questions regarding:
https://dexxter.be/kan-ik-aankopen-inbrengen-van-voor-de-opstart-als-zelfstandige/

What if you already incurred expenses as a private person and therefore do not have invoices with ‘Company number is pending’? And what if those invoices date from BEFORE the application for the company number? Can they still be submitted? And if so, how far back can they go?