Manufacturers usually make up their catalogs during the fall months preceding the year, and make their introductions at the SHOT Show (for distributors and dealers) and at the NRA Convention (for retail buyers). In these catalogs they put everything that they expect to produce sometime during the year. The also release prototypes to the "gunrags" for testing and promotional articles.
Some manufacturers (Taurus is one) tell their dealers and distributors up front when they expect to start making shipments. Others just look the other way and let you wait, and wait, and wait .... One well-known gunmaker made it a practice to announce a new model before it was even tooled. Then they'd see what the reaction was and set up accordingly. This I think was a little less then honest.
Let’s be fair. No company can put all of the new products into production at once. Be it cars, guns or whatever, these things are scheduled.