Meh. The whole fainting thing was about the PA warehouse, which was a building that was already there as far as I know.
Amazon leased it, they didn't make it.
It's not the warehouse in GA that's been causing problems for some people. And the GA one is the one the OP's sister is in.
Different states have different deals, but I know that DH's benefits didn't kick in at a mere 2 weeks of employment, and when I worked there in '99 they didn't then, either. But maybe it's different at the fulfillment center in GA.