This is a pet peeve of mine...but if you have to use the D word, it's Daza not Daia. Lactantius incorrectly used Daia, perhaps as a mistake or what had been passed down to him. Daza is an Illyrian name; while Daia is not. The name is also not part of his imperial titles, so there is no real purpose in using it--just plain old Maximinus will do fine.
for more on this see the article by Christopher Mackay--
LACTANTIUS AND THE SUCCESSION TO DIOCLETIAN