I always assumed pre-TROS that the reason that the First Order was named the First Order would be revealed as it being literally the FIRST ORDER Palpatine gave (possibly secretly or at least not publicly). That is, his first command upon ascendance to the Senate was the provision of a secret army, much as Order 66 was a secret order of his designed to trigger the destruction of the Jedi at the appropriate time. This makes him much more of a game player, with real foresight and planning, creating backups for his various schemes. Around that time Palpatine would have had access to active shipyards, plus cloning tech (which would more easily explain his return). It wouldn’t, then, be a stretch to assume that he was behind both the active First Order fleet in the first two sequel films, and his even more secret Death-Star-enabled fleet.