[Grammar] Just with present perfect

[Ab.m]

When I want to say that something has just happened "very recently" I use present perfect because something has just happened and has a present relevance or because it has just happened only?

 

[teechar]

I think you've answered your own question, in a way. By using "just", you're implying some kind of relevance to the present!
Otherwise, please give us a more concrete example(s) to consider.

 

[emsr2d2]

Both the past simple and the present perfect are possible with "just".

I just got back from Spain.
I've just finished my dinner.

Other tenses are possible, of course, depending on context.

I'm just finishing my dinner. I'll be with you in five minutes.
She had just finished her homework.