I've been telling myself for many years now I've wanted to create a company of my own and get out of the corporate misery.
I am a software developer by trade, and have worked with a few startups in the past.
Recently (past 5 months) I have been working on an idea, that is already a proven business model, and working on everything myself from the business end to the technical (dev) end.
I've saved up atleast 6 months of money, in order to live at home, and work on my product. My parents do not want this and think I should get a product together first and then quit ... which seems the most logical until..
You factor in: I'm working full time (40 hours) + doing 12-15 hours of commuting per week. This part will only get worse as I am given more responsibility at work and need to work on call.
How have you dealt with unsupportive (close) individuals to you (friends, family, etc.)?
Consider this a funding exercise. I would pitch them like an investor - that is, you need something from them (a roof over your head) and need to get their approval to work this out.
Understanding why they would rather want you to work full-time and addressing those issues directly would be better than dismissing them - unless you have an alternative housing arrangement, or don't mind a turbulent / at odds relationship until you prove your model. (Startups provide enough stress by themselves).
Getting to yes is a skill that is useful beyond this individual issue. Of course, no one here knows your exact family situation, but if it is like most, parents want nothing but the best for their children. Protecting them is also a reflex action - and understanding the situation from their vantage point (bad economy, people out of work, etc.) will help you explain your aspirations - and what plan you have to capitalize on this opportunity (and monitor its progress). If they are not tech savvy, then you have some teaching to do so they understand.
Edit: Here is a relevant inc article on how to convince your parents about your startup dream.
To answer your question, ignore all of them. My advice to you:
I have dealt with this situation with two of my friends. If you have the option of living with your parents while you do this, take advantage of the situation, quit your job after you've created all of your photoshop mockups and are ready to get deep into code (HTML, server-side, etc), and live on your money, launch within 3 months, and get a part time job after launching if you are desperate for cash at that point. Whatever you do, do not hesitate! It can make or break your chances of success.
I am proof of quiting my job and starting my own company
I get the impression you are serious about this because this catch-22 only appears when you start to try and put more and more time into the project and find your day job is really becoming an impediment. It is very tricky to build something outside of working hours in your "spare" time, because by then you're often mentally fatigued and the day job has gotten the best of your energy.
You can't expect your parents to understand that, but they don't need to. As parents they are predisposed to push you in the direction with the least amount of risk. Don't ignore them outright because they are your support network and in an indirect way they are your co-founders. Like jimg pointed out - think of it as a rehearsal for soliciting investors. If you want to get it off the ground you will have to weather all kinds of resistance and keep going.