I think “standard practice” is perhaps too strong(**), but Teknatool/Nova does seem to have had some challenges keeping up with demand one way or another. The Nebula seems to be hit most regularly. Skimming retailers periodically (since I’m also been planning on, now waiting for, my Nebula for some time

), the Neptune stocking situation has seemed better – but looking today I note that it’s back into “pre-order” territory at a number of retailers. Just recently, it had been in stock. If you’re ready to order, I’d call around to local retailers, e.g. if you have a Rockler in your vicinity, to see if they have stock on hand. Rockler nominally sells these via drop shipping on the website, but individual stores may have stock.
(**) By which I mean: I doubt that Teknatool has any desire to keep customers hanging. They’ll be losing business over that, period. It’s one thing for a tiny business (e.g. some woodworking tool makers) to do small batch production… but that doesn’t seem to be Teknatool’s scale at this point.