Depending on your chosen homeworking profession, how long can it take you before you become proficient in your work? How about an expert? A paper written by Anders Ericsson in 1993 suggests that on average, 10,000 hours is required to become an expert in your field.
Working 40 hours per week is the equivalent of 2000 hours per year, so 10,000 hours would take 5 years. This sounds like a long time, but think of it as an apprecenticeship.
American magician John Scarne explained in his biography that a particular card trick was easy, if you practice 3 to 4 hours per day, for 20 years. Scarne was just 19 years old. How was this possible? Scarne explained that he practiced 10 hours per day.
You don't have to work 80 hours per week, for 10,000 hours to earn an income. But you will probably get out of it, what you put in.