Have you been following the advice in the thread you linked? Different bodies take different amounts of time.
Mine’s been in for months, and I’ll still catch it moving on occasion. The FAQ page says it can take a year or more for the body to fully encapsulate it, but it should usually be far enough along by two months in for you to start heavy lifting or going shooting.
Took about two weeks or so for it to find a backstop (Not sliding farther away from the implant site) but took it I’d say a month-ish, for it to really stop moving without a lot of effort.
Over the two to four weeks post installation, the body will begin to encapsulate the tag with fibrous collagen tissue. To help this process along, you can take pre-natal vitamins 137, which help build collagen and connective tissues. During this time, it is important that you not perform any strenuous activity, put pressure on the tag, play with or poke at the tag, work out, spar, rock climb, shoot firearms, or grip anything with significant force as it can cause the muscles in your hand to apply unequal pressure to the tag and cause it to migrate under the skin.
From the FAQ.