For events in the future, the mapping between local wall time and UTC is not fixed (consider that Egypt recently cancelled DST on three days' notice), so if the time that matters is local wall time, you should not store your days as a UTC time stamp, you should store it as the local wall time with a zone or location identifier (generally use an Olson TZ if possible).

If you're storing time stamps (i.e. you care about how many seconds have elapsed / will elapse since / until the event), your strategy is the right way to go.