Date_query, particular case

Hi, i’m trying to make a query that call all posts published after 2 months ago. Looking WP codex I realized something like this:

$args = array(
	'post_type' => 'post',
	'date_query' => array(
		array(
			'column' => 'post_date_gmt',
			'after'  => '2 month ago',
		)
	)
);

I can’t test it. For you will it work? My only “?” is in the after => ‘2 month ago’. Or should it be ‘2 months ago’?
In Codex was only wrote “See WP_Date_Query::build_mysql_datetime()’, “

but found anything…