Morality and legalities aside (don't trust internet strangers for that stuff anyway), I have some comments.
1. All employees should do the very minimum amount of work possible to sustain the relationship with their employer and meet their own personal goals. Check all the boxes, but don't go above and beyond unless there is a direct benefit to you (promotion, bonus, etc). If you can check all those boxes in just a fraction of the time, great!
2. If you're bootstrapping, keep the paycheck job as long as you can. Keep it, even if you hate it, until you HAVE to make a decision about working as a Founder or as an Employee. The longer that paycheck is coming in, the longer you'll be able to survive on ramen profitability. The more money you save (you're going into this with savings, right?) the better you'll fare in thin times.
Working for the man sucks, but running a struggling business while barely surviving can be worse. Running a struggling business with financial cushion can mean the difference between succeeding and failing.