I believe nobody is sure if the VA will start immediate after the update, or sometime later during the day. I would speculate that it will start close to around the update time.

We already have Altair and Amira...Tormenta will be added in the next week or so, and I feel Zaldia's promotion will probably start towards the end of the Month. Then it will probably go to Bucephalus event sometime in October (I'm guessing towards the Middle of the month).

So I'd say the chance is high IF the Team is planning on re-releasing the Legendary Horses...it would probably happen sometime around late October to the end of the Year. Though just how they would do it is a mystery, as there are many options:

1. Offer missing tack items for sale directly in the Black Market (ex. Purchase Amira's Ear Bonnet for 5 passes)

2. Offer missing tack items in the Horn of Plenty/Titan's Challenge/Golden Fleece (though the challenge to this would be making sure that players don't get doubles of things they already have/get the Legendary tack they want.

3. Offer tack sets in a Pass Pack deal (Sort of like the Lucky Day or Olympus packs of years past - buying the Pass Pack gets you the full set of tack, as well as some other goodies. Or even one that lets you choose which tack pieces you get (ex. a Player is missing Tormenta, Zaldia, and Bucephalus' Ear Bonnets...you can choose to get only these pieces)

All we can do though is wait and see.

*Please note - all Time Frames mentioned in this spoiler are just Speculation! I do not guarantee that any of these events will happen at the times I have said - I simply came up with these times based on how things have run recently (that is, a promotion is around for 2- 3 weeks, then we get a small break before another one starts)

The Vintage Apple contest will be coming on the 8th (tomorrow) to celebrate the 10th birthday of Owlient, you have only one day to get it; no one knows when this item will come back. If your not on, then you don't get it.
However, you may have another chance to get it if a player who has a VA but doesn't want it puts the item up as a UFO - that is another way you could obtain this item.