So the thing I’m wondering is does it go 000AAA0, 000AAA1, … 000AAB0, … or does it go 000AAA0, 001AAA0, … 999AAA0, … 000AAB0, etc.?
I first lived in California during the waning days of the 1XYZ123 plates and while I occasionally saw older cars with 123ABC plates, I never knew the order those were issued.
1963's ABC 123 came first[1] and invalidated earlier plates (but they can be used again under the year of manufacture plate program [2]), when those ran out, they did 123 ABC; when those ran out they did 1ABC123. When all the 1s were issued it was time for 2, etc.
with a trailing 1-9, it will likely be the same. You have a preview with commercial plates which were 1A12345 and are now 12345A1
(edit: linked to two pages with lots of good info)
I first lived in California during the waning days of the 1XYZ123 plates and while I occasionally saw older cars with 123ABC plates, I never knew the order those were issued.