Get category ordered by last post date

Hello there,

First time for me, please excuse my approximate english.

I have a website in local for a while and I can’t get to work one of the feature i wanted for it. The feature : get the category ordered by the date (of the last post in this category)

Let me explain, i have 5 main categories (say Local News, Arts, Music, Itw and Misc for exemple).
I have a loop in the index that retrieve the 2 last posts of each category but with 5 queries. (wich is…not great for now)

$args = array(
'cat' => 1273, //i change the cat id - this is the value that needs to be variable in my future query
'showposts' => 2,
'orderby' => 'date',
'order' => 'DESC',
'post__not_in' => $latest->posts //i have a slider and do not want my posts to be in double
);
$the_query = new WP_Query($args);
if ( $the_query->have_posts() ) : while ( $the_query->have_posts() ) : $the_query->the_post();

etc

I want this order to change regarding the last post date of each category.

Lets say i had yesterday :
-Local News posts
-Arts posts
-Music posts
-Itw posts
-Misc posts

Today if i post in Music :
-Music posts
-Local News posts
-Arts posts
-Itw posts
-Misc posts

And tomorrow if i post in Misc :
-Misc posts
-Music posts
-Local News posts
-Arts posts
-Itw posts

And so on.

I hope my issue is understandable.

I search for a while now how to do it but it seems that nobody ever wanted to do it, or had any trouble while doing it at least !

Can anyone help me on this one ?