If you have a family, in the most kind way you can think of, learn to say no. While you are at home trying hard to work, everyone will think you have lots of free time.
Find a place where you can work quietly when you really need it. Preferably not at home, not at a coffee shop, not anywhere you could be interrupted.
Find a mentor/buddy. Someone who knows more than you do. When some server configuration bullshit gets in your way, when some framework bug stops you, when some Ruby version 1.8.7 patch 154 won't work with Delayed Job (a made up example) you'll need someone with the experience to help you.
Wake up at the same time everyday. Got to sleep at the same time every day. Eat breakfast. Exercise. Throw out your television, don't visit HackerNews or reddit except once a day.
Use a managed hosting service avoid VPS unless you are already a good sys admin.
"Start Small Stay Small" has good advice here. Don't be put off by the title if you want to grow big with VC money etc. It's still a great book. http://www.startupbook.net/
Agree about the validation. You can try to sell it before you have much of anything. A screen is all you need to try to sell it to people. Talk to as many people as possible. It is so easy to just sit in a corner and code - that is really dangerous.
I also gave myself a one month window at the end of the time frame to find a job. So, in your case, I'd only give you one month to work on your startup before needing to go look for a job.
Given that you've already quit, you may want to reconsider getting more cash in the bank. Your living expenses are one thing, but depending on what you're doing you may need to pay for other skills (design, devel, etc), and cash is king.
What would be your plan after the money ends in 2 months? Go get another job? 2 months doesn't seem long enough to develop and test your ideas, nor to make something that would bring in a livable wage, let alone profit for growth.
If you've already got a product/service, and the 2 months is just to get sales in the door, that might be a different story, but cashflow can take a while to establish even then.
You can do some freelance work while working on the business, but they often interfere. Focus on doing one or the other for a while. Again, everyone's different, but if it was me, I'd focus on getting some billable freelance work in first, getting more cash piled up, then focusing on your idea.
Others may work differently, and only you can really tell what's comfortable for you. But I've learned that it's much easier to think clearly when there's several months of cash in the bank at minimum.