The interpretation is that since the character can now cast 2nd level spells, it gets extra slots at 2nd level due to Elven Generalist and Domain Wizard, and the cycle continues from those two slots.
However, even if it works in theory (big if there since the wording definitely isn't agreed upon to actually give that ability) it's only good for theoretical optimization. There's no chance any sane DM is going to allow getting 9th level spells at 1st level. Trying a trick like that is something that will get most people simply banned from the table, and rightfully so. Since this discussion is about actual play across many tables who will most assuredly not allow that kind of cheese to work, the trick should be disallowed.
By the way Cyclone, when you're the one making claims, you're the one who must show the entirety of your claims, preferably with citations, if you want people to actually take you seriously. The onus is on you to show your work.