Arizona House Bill 2484 moves the primary from the 10th Tuesday before the general election to the 11th Tuesday. On February 20 it passed the House Rules Committee. If this bill had been in effect in 2016, the primary (for all office but president) would have been August 23, not August 30.
If the bill becomes law, the petition deadlines for newly-qualifying parties, and for non-presidential independent candidates, would become one week earlier.
What reason would they have for moving the primary just one week earlier, does it really change much?
Election administrators always desire to have as much time as possible to get ready for any election. Probably that is the reason for this bill, to give them more time after the primary to prepare for the general election.
Overseas ballots have to be mailed 45 days (6-1/2 weeks) before the general election.
Under the old calendar there were 3-1/2 weeks between the election and the mail out date.
During the 3-1/2 weeks, the results have to be canvassed, provisional votes processed, ballots printed and proofed, and readied for mail out.
If the federal government operated voting centers overseas, the 45-day mail out could be reduced, since they could verify identity, and also provide return of voted ballots to the US.
Alternatively, if Arizona would adopt Top 2, overseas voters could vote a ranked choice ballot for the primary which would only be used if another ballot was not received. There would be no need to mail a second ballot, since overseas voters can check to see who qualified for the runoff (if any).