Plywood is a weird product, as it's made from multiple laminations. I don't think a blanket statement applies just to imported goods, but rather how those goods were packed, handled and stored.
The box stores get quite a bit more inventory than a local hardwoods supplier. How old the product is, and how dry the plies were when laminated can have a great effect on how stable it is.
Once you get your order, whether one sheet or 10 sheets, I wouldn't lay the first piece on the floor directly, especially if the floor is bare concrete. Laying the goods flat would be the best way if you have the room. I would sticker the first and all subsequent sheets especially if you won't be getting to them for a while. Keep weight on the top sheet to keep them all flat. Being stickered allows airflow around the entire sheet.
If you don't have the room you can store them on an 8' edge, as vertical as you can, and sticker in between them and clamp the top edge of all the sheets together tightly. The sheets will stand on their own, and you can do this near a wall, allowing as much floor space as possible.
When cutting parts, visually determine any bowing or warping and try to configure the usage to your advantage. Example..if a piece is to be used for a shelf, or top, a bow up will likely be a more physical attribute, to resist deflection.
Most all my sheet stock comes from hardwood and plywood distributors, not the box stores, and there is still that problem that we try to prevent if at all possible. If you keep the sizes with reasonable dimensions that would help.