How does the timing of Order Domain’s Voice of Authority work?

The Order Domain cleric from Tasha’s Cauldron of Everything has the Voice of Authority feature. Part of that feature states:

If you cast a spell with a spell slot of 1st level or higher and target an ally with the spell, that ally can use their reaction immediately after the spell to make one weapon attack against a creature of your choice that you can see.

Immediately after the spell _____ ? Is cast? Targets the ally? Affects the ally? Ends?

For spells like healing word, the intent seems simple. The spell is instantaneous, so:

  1. You cast healing word, targeting your ally.
  2. Your ally is healed.
  3. You use Voice of Authority. Your ally uses their reaction to make an attack.

For spells like dawn, things get a little more complicated. For simplicity, I’ll assume that all creatures within the area count as targets. It seems like the initial cast of a duration spell would work like this:

  1. You cast dawn, which includes one ally in the area.
  2. Your ally rolls their save and takes damage.
  3. You use Voice of Authority. Your ally uses their reaction to make an attack.

But if you maintain concentration, the spell continues:

  1. Your ally (the same one as above) takes their normal turn in initiative.
  2. Your ally ends their turn.
  3. Your ally is still within dawn, so they are targeted/affected (?) by the spell again.
  4. Your ally rolls their save and takes damage.
  5. (?) You use Voice of Authority. Your ally uses their reaction to make an attack.

Voice of Authority restricts you to only one ally affected, but (potentially?) doesn’t restrict that one ally to more than one attack.

For some additional weirdness, allies could be targeted/affected only on subsequent turns:

  1. You cast dawn, which includes no allies in the area.
  2. Your ally takes their normal turn in initiative, during which they enter the area.
  3. Your ally ends their turn in the area.
  4. Your ally is targeted/affected (?) by the spell for the first time.
  5. Your ally rolls their save and takes damage.
  6. (?) You now use Voice of Authority. Your ally uses their reaction to make an attack.

My question is: how does the timing of Order Domain’s Voice of Authority work, particularly for area spells with a duration? I expect to be using this class feature at a table that sticks closely to RAW, so it would be helpful to know what the rules say precisely. If the rules are unclear or undesirable, then tested rulings are also welcome.