Of course, moving your army to the border of another country is sending a message, but for it to become a real threat, you need them to believe you are actually prepared to invade, or at very least leave them guessing, and use that in the talks earlier this year. Putin was doing exactly the opposite by telling everyone he had no intention to invade, thus deflating any threat, whilst he got his ducks lined-up ready for the invasion.
It's possible that it may have been his original plan last year, and that didn't work, so he moved forward with planning the invasion, transferring more & more resources to the border and into Belarus early this year.
There's no way he just suddenly decided to invade in the last few days before he did, as suggested in that article as a reason why 'most Russian soldiers were not told they would be invading Ukraine until the last moment (or, in some cases, not at all)', etc.
He thought invading was going to be a piece of piss, victory within a few days, hence why it was so haphazard, the planning went wrong, plain & simple.