How long does it take you guys to develop your niche?

[kenpachi]

If you guys could so kind, as to share your experience in how long it takes on average from the time you pick a niche, to the time you turn a profit, or pull the plug and move unto the next niche.

Say for example that you have done a lot of research and found a great niche and you decide to go for it. How long does it take to get into the "game". Second, how long does it usually take to turn a profit or until you decide that it's just not going to work and pull the plug on it?

Thanks!