Hi @federicolugli, welcome to the community!
In order for you to trigger a Flow in Klaviyo based on a product arrival, you need a Custom Event that signals from your shipping carrier to Klaviyo when a product has arrived and left the carrier.
There are a few Klaviyo Technology Partners that I’ve worked with that support this as part of their integration into Klaviyo.
But there may be many others in the Integration Directory : Shipping/Logistics that you may want to explore.
Alternatively, if you only need approximate times an item arrives and depending on which ecommerce platform you have, there is typically a “Fulfilled Shipment” event. This typically happens at the time you mark an order as “Fulfilled” and have a shipping label produced and ready to go out.
You can approximate the time after an order is Fulfilled (example: 3 Days Delay) for when you think the customer will receive their order and add this as a time delay in a Flow that’s triggered on “Fulfilled Order or Fulfilled Shipment.”
Hope this helps!