Hi there!
I took my (then) four month old on a trip from California to the UK (8hr time difference). We just went cold turkey on the time change. As soon as we got off the plane, I behaved like it was the time it was in the country we were in and 'forgot' where we came from. It was too big of a time change to adjust his schedule by 15 minutes or so a day leading up to the trip. Actually he did really well. It took him two days to convert when we got to the UK and five to convert when we got back.
We did his wind down routine at the same time (7PM) in the UK as in the US and had meal times at the same time. Obviously follow you little one's cues and don't try to keep them up if they really need to sleep or deny them food if they need it. I fed my son every 4 hours regardless of if it was day or night if he was awake and 'asking' for it. I didn't do PU/PD without feeding him at night if he woke up.
Another thing that helped me was taking my son out on lots of outdoor walks during the day and being really strict about keeping it dark when it was nighttime. The light, or lack of it, helped him realize it was day vs night etc.
Another bonus was that I was the least jet lagged I have ever been when traveling between the US and UK! Getting little sleep in general makes time differences a cake walk for an adult
Good luck!
Jill (and baby Davis)