Edit: if you are going to do this by yourself, please do let us know in this thread how it went for you! I hate to be an anecdotal n = 1 'experiment'.
Note: this technique has some risks. Especially when you practice by yourself. The biggest one is that scientifically speaking, experts are a bit unfamiliar with it. I can only offer anecdotal experience. There are some articles written about it [1], but I wonder if they go into the risks of the technique (I don't think so, I was one of the people in the experiment).
Yea, it's exactly as described there. The tinnitus will be temporarily gone in step 3 (when you hold your breath). Or at least, that is the case with me. It'll come back after you took your breath in step 4. So it's a temporary relieve, unfortunately.
In any case, there are a couple of checks you can do to see whether step 3 is working as intended.
1) You are capable of holding your breath for more than 1 minute and 30 seconds. Note: if you go over 2 minutes, you might want to have someone by your side who can shake you a bit. I sometimes faint around 2 minutes and 10 seconds, I wake up without assistance as well though, but better close of small risks. Shaking works quite well (there was one case where I saw it almost fail, the person was unconscious for 3 minutes and then got to consciousness after 3 minutes of being shaked, normally it takes about 10 to 20 seconds, except for this one case).
This is a hard requirement.
2) You feel a tingling sensation in your hands, feet or body. This is not only my experience, it's almost everyone's experience who did this. So this is a semi-hard requirement.
3) After doing this for 2 rounds, it is my experience that my body naturally understands how this type of breathing works. I naturally get into a flow of things. In a sense, I can only describe it is "my body is breathing like my life is depending on it". It's a very rare sensation, and definitely not similar to swimming under water and almost running out of air.
This is not a hard requirement at all.
[1] https://www.pnas.org/content/111/20/7379