Sinanju mix plans will be out whenever Wasabii feels like it. You can get the Sinanju (or its mix plans) in events, currently, but not the in-game shop. It could be next month, it could be several months from now. They kinda have a pattern, like in THEORY, we were supposed to get Arios mix plans this month (instead we got Cherudim) so we really have no clue.
As for the mix plans themselves, check the various wikis all over the net. This is the one I think most english speaking players use.
Sinanju is one of the harder suits to mix. Char's Gelgoog is the key, and for the plans you need to go through a painful quest chain, and the Key for Char's Gelgoog is the Gelgoog Commander, an Expert Mission suit.
Federation sympathizer and GM lover. NEVA GONNA CHANGE.