It does take some time but as we are all individual it's impossible to say exactly how much time; it could be months or, I suppose, even a couple of years. Mine is not completely risen but is well along. When you begin this process, one of the things you will notice is that you will feel great heat; that is one of the indicators.
Be sure you have mastered power meditation, protection, etc., BEFORE starting to raise your Kundalini. You need to be prepared; it's not something you should just jump into, tempting though it may be. It's highly advisable to work with you guardian demon when embarking on these advanced exercises.
