I have the Mac version of the game, upgraded to .05 on May 4, and up until today only had one family going. I purchased the trial on 4/29 and got the full version on May 3. I had paused the game a couple of times prior to getting the full version but not at all since, and I never alter the time/date on my computer, so no "time-traveling" is ever done.
I opened the game this morning around 9:00-9:30, bought a store item or two, and left it running all day in the background. By 4:30 p.m. I still had no store restock. In the meantime I had started three more families periodically throughout the day. Although I didn't time them as closely I don't think they got the 4-hour restock. I will test them more thoroughly tomorrow. I am absolutely sure that it was at least 8 hours for my original family to get their store restocked.