Present oder past perfect

Hallo ich bin mir nicht sicher welches die korrekte Zeitform in meinem konkreten Fall wäre.
(Ich soll einen article über eine Erfindung schreiben.) Die Textpassage lautet: First I want to tell you how I came up with the idea. I have a farm and my cars get dirty every day and so I had to clean them daily. I didn´t have/ hadn´t had enough time to clean them. That´s why I have/had employed a worker to clean my cars. But after a few months it was too expensive for me. I was worried, because I didn´t have/hadn´t had time for other things. One day I had the idea of a car-wash robot. --> ist das nun vorzeitig zu verstehen also past perfect, weil das doch vor der Zeit der Erfindung so war? Bitte um eine Begründung für die zu verwendende Zeit. Thanks :)