Shopify Marketplace Connect publishes updates immediately, however, these updates typically take between 5-60 minutes to be processed by the marketplace. This includes inventory edits from Shopify to the marketplace (e.g. more goods received).
If you have fast-selling inventory, consider using the Quantity Buffer option in the inventory field to reduce the risk of overselling. For further inventory information.
For further assistance, please reach out to firstname.lastname@example.org