"When do the deliveries arrive?"
Translation:Hvornår kommer leveringerne?
As much as I can see, in this context "ankommer" and "kommer" have the same meaning, so I suppose it doesn't really matter which one you choose. Both are verbs indicating that something or someone is or will be arriving at a particular place. Hope the following links help. http://ordnet.dk/ddo/ordbog?query=ankomme. http://ordnet.dk/ddo/ordbog?query=komme.