Before we get into this topic we will need to talk a bit about how synchronisation works in general, in the following order.
Customer purchased a product that is either part of an Inventory Group or Bundles
Shopify sends an order notification to Connected Inventory app
Connected Inventory app computes which product requires an inventory sync and by how many
Connected Inventory sends an inventory update to Shopify
Shopify receives and completed the inventory update.
The delay depends on how fast each component in step 2 - 5 can complete the task. Unfortunately we're unable to guarantee the amount of time it would take. It is because step 2 and 5 depends on how fast Shopify behaves rather than Connected Inventory.
But we're gathering statistics and hopefully we can publish some data we have observed.
Bundle Groups has other types of delay which will be mentioned in below sections.
The inventory of Products (or variants) in Inventory Groups will be synchronised in the following scenarios: