My only advice is to get them on the destination schedule immediately (meaning if you need to wake up from naps to keep the schedule, do it.)

We took my 11 month old (same sleep schedule, 12h at night with 2 1.5-2 hr naps) to Europe from the West Coast, and she was fine both ways. First night she woke up, but didn't go in and she settled herself. First nap the next morning was on schedule (9am) but I did have to wake her at 12 to make sure the 2nd nap could be fit in. Other than her wanting to sleep longer that AM nap, she was right back on schedule.

Also, exposure to light during the day to help the body regulate (works for all of us really.)