This is right. Strict embargoes are only for big publishers, really. With everyone else, the bookstore puts it on the shelf when they receive it. Actually, even with big publishers, it only matters for big books. Alcatraz books typically showed up on shelves as many as 6 weeks early. And with Brandon's Tor books, they didn't get strict until Way of Kings.
Buying it early can hurt a book's ranking on bestseller charts, because initial sales are spread out over a few weeks instead of being all in one week. However, we don't know anything about the trade paperback fiction bestseller list, which we have never tried to compete on.