when are leakers allowed to post spoilers ? are you working for shueisha ?
LOL no
they obtain it through some link in the chain who give it out to someone, that someone passes it on etc, it's all informal
Also it's just code of honor, they COULD leak right now, even two days ago when they got it but they won't because they fear a DMCA strike or getting sued
Technically even releasing spoilers on e.g. Saturday, the day before the chapter officially releases on Sunday is DMCA/Sue-worthy but Shueisha is lenient in that regard.