Why does Vine sometimes get claimed overnight and sometimes sit for weeks? Also, how do sellers launch with reviews already attached?

I did a Vine seed ASIN last year. Registered it in July, and it got claimed in one day — but my inventory didn’t arrive until October. I used that ASIN as my seed and merged it with my main shipment that came in November. So yes, my main listing launched with reviews already on it.
But Vine reviews don’t all come back at once. Out of 20 units I sent:

• 5 reviews came back the first week
• 10 more over the next month
• The last one didn’t come until December

Also, only 16 actually left reviews — one person gave me a 1‑star because they received the wrong color (my mistake). So even Vine isn’t a guarantee of perfect reviews.

Here’s how price affects the timeline:

• Under $10: Usually hits the public pool in 1–4 days. ~70% chance of being claimed within 20 days.
• $10–20: Can take 10–20 days to hit the public pool. ~50% chance within 20 days.
• Over $20: Often stays in seeding for 20+ days.

Lower price = faster claims. Also, broader categories move faster. Small niches can take much longer.

It’s not magic — it’s a two‑phase system.
Phase 1 — Initial seeding (first 1–2 weeks)
Amazon doesn’t throw your product into the big pool right away. First, they email a small group of Vine Voices whose purchase history matches your category. If they like it, they claim a few units. If not, it sits. This is why you sometimes see slow, trickling claims — you’re in the initial seeding phase, and the match isn’t clicking.
Phase 2 — Public pool
If your product doesn’t get fully claimed in the seeding phase, Amazon pushes it to the public Vine page where all Vine Voices can see it. Once it’s there, it’s a volume game. If your product is decent and priced right, it can get claimed overnight.
So why does it vary?

• Low‑priced products ($10–20) tend to hit the public pool faster (sometimes within days)
• Higher‑priced products can stay in seeding for weeks
• If your category has a large Vine Voice audience, you’ll move faster

Now on the “launch with reviews” trick:
You run two ASINs:

• Seed ASIN — send via air freight, register for Vine immediately, price it low (sometimes with a big coupon) to get it claimed fast. You might lose a little money here, but you’re buying reviews.
• Main ASIN — send via ocean freight, slower arrival

Once your seed ASIN gets a handful of reviews (usually 5–10), you merge it as a variation into your main ASIN. When the main ASIN goes live, it already has those Vine reviews attached.
But a few risks:

• Review cap: If you register for 30 units, you’ll only show up to 30 reviews. Merging another ASIN with more won’t stack past that.
• Price swing risk: If you priced the seed ASIN very low, merging it can confuse Amazon’s reference price system. Sometimes your main ASIN loses the Buy Box or gets paused. Fixing it requires supplier invoices and packaging photos — a headache.

It’s a common approach, but not without risk.