As others have said, there's no rush to do anything. In fact, just having your suicide method ready at hand is a significant step, and you can let it be until the day you are ready, be it in one week's time, or 30 years from now. At least that's how I'm personally thinking right now - I wish to have a method ready, and then I will use it if I get ready to do it.
It's not always clear why one wishes to end their life, but I have always been afraid of dying a natural death, because I'm imagining that it involves suffocation or something similarly dreadful. Therefore, it's better to choose another way of dying, which suits oneself better.
Are you feeling like this because of depression, or did you get all those methods in place as a cry for help? From what I can read, you have already thought this through, at least, so the decision is up to you, but I hope that you are content in any decision that you ultimately make.