I would be interested in what the term "channeling" means to you. If you are speaking of mediumistic channeling, then I have never done that. I am not sure that I have the capacity for that type of channeling due to the fact that I am very strong-willed. If you are speaking of "drawing down the moon" or accessing divine energy, I have some experiences. My experiences have varied depending on the particular entity involved. I don't recall how long it took to have these experiences - probably 5 years of dabbling with meditation and witchcraft before I had a full-on vision/knowing experience. I am not a professional witch so my spiritual practice has been tempered with the need to support and raise my family. Perhaps in your case, it will be quicker.
Like EM, my experiences have not always been intentional. The most powerful episodes were spontaneous and not really pleasant. I do think that the years of preparation were helpful in preventing any psychological issues for me. Typically, a serious episode is preceded by a period of agitation where I have the feeling that there is something I should know but can't figure out what it is. I tend to be overly emotional leading up the episode as well which is an indicator that I need to make time to "get it".
And yes, I do have ritual jewelry and other tools that help me get into the mindset for trance work.