Starbucks makes all their lattes with 2% milk but you can use any kind of milk you like.
Homemade vanilla syrup can be made ahead of time. Make a batch and use it to make several Iced Vanilla Lattes.
Instead of homemade, you can get vanilla syrup directly from Starbucks by going to any of their locations and asking if they have any vanilla syrup available for purchase. They’ll sell it to you if they have enough in stock. It should cost around $14.