Do not tell anyone you're working on an idea! This is extremely important. Why?
Your co-workers -- they will get jealous. At first they will be impressed. And you will think, wow, me working on this makes me look good at work, so I will share it with more people. Suddenly you'll feel this article was bullshit because your manager will tell you "wow, you created this at home!? that's awesome!" -- and you will think you're bound for a promotion at work for working on your side project. The reality is after the fizzle and the novelty disappears your co-workers will judge you. When you come to work half sleepy they will know you were home trying to build something to become famous -- to escape them. When your manager sees you leave work early, s/he will think, what a slacker -- going home to make more money instead of working with the team. After a year everyone at work will have a negative perception of you as a selfish unreliable person. All of this because of envy.
To your friends -- they will want to hang out with you even more. They say misery seeks company, and its true. When they know you're having fun with your own project they will want to stop you to "watch the football game" or whatever.
To the naysayers -- its REALLY hard to tell what people's reactions will be to your idea. In the short term everyone will be positive, later the "naysayers" will make your life miserable. Naysayers are those that without data or evidence pull you down. You can't tell who these people are -- so its best to not tell anyone.
DO tell your wife or those that define your life -- there are only 1 or 2 people in your life that define your life. For most it coudl be their spouse. For me personally its three people -- my mom, dad, and girlfriend. No one else defines my life. I very quickly and lightly mention I'm working on a side project. I only bring it up once every one or two months. No more.
What you're looking for -- in this period of silence you need to find MARKET VALIDATION. You need to make sure your're not crazy. You also need evidence so that when you show it to a naysayer you can convince them otherwise. This will help you with getting future customers, see "Getting Your First Customer."
From a different angle -- if you fail with your project, everyone at work will know you as "that guy that has many failed side projects" and if you succeed, not only will people get jealous, but they will ask you for favors and waste your time. Once they know you succeeded, they will ask for help with their own side projects -- complete waste of time.