The majority of hiking groups meet in Cusco, Peru, before beginning their journey, so this will most likely be the city you will fly into. However, this area is at a much higher elevation, and your body will need time to become acclimated.
Some locals advised us to chew on coca leaves or drink coca tea to combat any altitude sickness. Be aware though that if you're not used to these leaves, as we were not, they can upset your stomach.
To be on the safe side, I recommend arriving into Cusco at least a few days before your hike so you can properly adjust. Take these days to leisurely explore the beautiful streets of this historic city and embrace the wonderful Peruvian culture.
Just remember to allow yourself plenty of time to rest up for what should be a remarkable journey. Hopefully, by taking these tips into consideration, you will have a much more positive adventure than what I experienced!