Turn the instruments on at least five minutes before launch. This should provide enough time for the GPS to acquire and apply the GPS to UTC time offset before you begin your flight.
The other thing you can do is d/l your flight at 4s interval instead of 1s. This should mask the time jump as far as OLC is concerned. This is only an OLC problem... your files are still valid for records, contests, etc. You can (probably) fix your existing OLC flight if you do this soon.