Dragons of Legend will be out on April 24th for most of Europe, and April 25th for the US and others.

YCS Paris will take place on April 26th & 27th, which may cause some trouble for players who want to play cards of this set.

Therefore, Konami decided to not allow Dragons of Legend for the Main Event of YCS Paris. But, Dragons of Legend will be legal during the Public Events of YCS Paris.

Legal Date for Dragons of Legend for :

– Local Tournaments across Europe (including WCQ: Regionals) ==> April 24th
– Local Tournaments in UK & Ireland (including WCQ: Regionals) ==> April 25th

Source: http://www.yugioh-card.com/uk/news/ycs_paris_legality.html