The uses of πια

Can anyone explain with clear examples the different uses and nuances of πια. I have tried, with limited success, to trudge my way through the Πύλη definitions. I need something simpler and clearer.
Does this from Wikipedia cover the main uses:
πια
any more (from a given time onwards)
Δε σε θέλω πια.
I don't want you any more.
already, now
Ο Γιώργος έχει μεγαλώσει πια.
George has now grown up.
already (as an intensifier), at last.
Ησύχασε πια!
Be quiet, at last!

Synonyms
πλέον (pléon)
επιτέλους (epitélous, “at last”)

...
Here's another one for you: Πώς μεταφράζεται το "Τώρα πια" στα αγγλικά;

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Sorry for this, but I can't resist the vocative comma variation that perfectly describes your frustration :

Από τα πολλά που μου 'χεις καμωμένα
δε σε θέλω, πια, δε σε θέλω, πια
τα σωθικά μού τα 'χεις μαυρισμένα
δε σε θέλω, πια, δε σε θέλω, πια


Δε σε θέλω πια: I don't want you anymore ≠ Δε σε θέλω, πια: I don't want you, πια

Thanks, 'Man, and for the link. This small word, like να, can cause the beginner great confusion. See SBE 'on a wing and a prayer #16.