My grammar book suggests that when using words like just, that you should “always” use present perfect. So the correct form should be I've just arrived according to my book.
Is this true?
I ask because I see a whole lot of people using I just arrived all over the place. I therefore cannot help but wonder whether this is an incorrect form that is somehow nonetheless in wide use by native speakers, or whether it's also a correct form just with a subtly different meaning.