When to Start Creating Monsters

[1oldtymer]

I suggest you defer creating/absorbing monsters (except for one you need to unlock a progress point) until you unlock what I'll call the "post-game" dungeon (Nihility Cave).  At that point it will be much easier and quicker to create monsters, and there is really no need to do so any earlier.   Unless you want to attempt to collect the entire 160 gallery of monsters, it is not necessary to create many monsters in order to exhaust the game events.  There are some bonus monsters/items if you do complete the gallery (more detail in my "Overview" post).