This is going OT a bit, but here goes: I've taken it a few times for other reasons before I got the current, more severe, tinnitus. I've only recently re-started it for seeing if it helps with the tinnitus I got, and have done two infusions with that treatment target.
I noticed an immediate improvement during the procedure, but that might as well be due to the other ingredients (n.b. that Midazolam is a benzodiazepine for example). Then there's a more subtle change (slight decrease in loudness / intrusiveness) which seems to last a bit longer now after the second infusion. Effect of the first one lasted maybe four days.
I have another procedure planned and, if successful, will likely extend it to six total (which is what the clinic is willing to offer).
I tend to listen to very calm music (
https://somafm.com/player/#/now-playing/dronezone) during it. There is a theory that Ketamine boosts neuroplasticity slightly and temporarily, and I'm trying to train my hearing to distinguish better between "real" audio and hallucinatory audio (i.e. the tinnitus) so that I eventually can ignore or even "unlearn" the latter.