Board Thread:Naruto Discussions/@comment-4688597-20140416230405/@comment-945885-20140422225229

Lately I think the raws have been purchased, possibly breaking store date (official sale date is Monday, so Sunday in the West) but legally purchased.

The 674 spoilers are from WSJ's ongoing promotion. According to this page, you can only choose to preview one page of the next chapter, and some pages are declared NG (no good / off limits) by the editors. So what most likely happened is one or more people managed to get all of the preview pages by doing the preview multiple times.