An adverb is usually put either after the first auxiliary/modal verb if you have an analytical form or before a notional verb if you have a simple form. However it can also occur at either end of a sentence.
We sometimes go to Spain.
We'll sometimes go to Spain.
Sometimes we go to Spain.
We go to Spain sometimes.
In your sentence 'immediately' can be used either after 'can' or at the end of the sentence. BTW I think you need 'the' with 'shipment'.