Traveling internationally with a huge time change like 9h is rough. We do it every year (or more) with Sofia since we travel from Los Angeles to my home town of Barcelona. My main tip is to take it day by day and understand that i can take over a week to be back on schedule. Here are my main tips.
1. Young babies naturally sleep so often during the day that they adjust more easily. The older, the hardest it’s been.
2. Adjusting meals is really important, getting her to even want to eat during the day, and not be hungry all night, took a few days! Instead of meals, try to keep offering healthy small snacks more often daytime, to switch the hunger over. This also keeps the energy levels up and encourages them to sleep longer, rather than waking from hunger. But tip: grab some healthy snack options to have at the hotel/apartment because chances are, you will all wake up hungry in the middle of the night for the first few, and you'll NEED to have things around!
3. Make sure your trip is long enough to allow a stress free adjustment. I would never come to Barcelona for less than two weeks.
4. Jet lag will also vary depending on what local time you land, for example, there are only direct night flights coming over from LA to Bcn, so she always sleeps through them. Which is great & makes a 12h flight way easier. However, we land when it’s 6pm in Bcn, and she just woke up from her “night” flight sleep. So adjusting is way harder.
5. Once you arrive at your destination, let your baby nap when tired. But try your hardest to not let them nap much longer than would normally at home. And remember, if they sleep all day, they’ll be up all night.
6. Don’t spend all day in the hotel or apartment, it’ll only get you more tired. Get out and explore, even if it’s just the local neighborhood. Natural light will help reset and give you energy.
7. Try to do the same routine you would at home to prepare baby for bed. Bring along anything that baby associates with sleeping like a stuffed animal, sleep sack, bedtime books, white noise.
8. Even if you go to bed later, try not waking up too late. But also make sure to get some proper sleep hours so they don’t want to sleep all day and they are ok with their regular nap. Slowly wake earlier too.
9. Try to do more outdoor activities and play. Even local parks. So they are physically active and not always in the stroller.
10. Try to go to bed when your toddler does, you never know when they’ll wake and they may wake in the middle of the night for a few hours, and go back to bed... so you need to be rested too!