Countdown timer not the same for everyone

do you have a caching plugin installed?

The time used for calculation is based on the server’s time…. except your caching plugin is stepping in, and returning the time that the server was when the cached files where created.

You will need to prevent any pages with the countdown from being cached. Add the page’s URI to W3 Total Cache’s “Never cache the following pages” box on the Page Cache Settings tab.

Other than that, you can follow along with–and participate on–this thread: http://ww.wp.xz.cn/support/topic/plugins-that-require-access-to-current-server-time