Google quietly announced on Google+ that you can now set your timezones for your AdWords conversion imports. Google wrote that you can "set time zones for your conversion imports with time zone IDs."
The time zone IDs are listed over here. This should help make sure your conversions are reported on the right day.
Google added, "daylight saving time or collaborating across multiple regions can cause unexpected upload errors. Having the right time zones set for your conversions in AdWords can improve reporting accuracy. That's why you can now specify time zones for your conversion imports with timezone IDs."
One caveat:
You still have the option to enter the difference between your time zone and Greenwich Mean Time (GMT offset). In addition, you can set a single time zone for all your conversions, or different ones for each conversion.
Forum discussion at Google+.