I have to be at Milan Malpensa Airport at 7:30 am. Is there an early train from the Central Train Station to the Airport?
I always take the shuttle bus because it runs every 20 minutes, but many people do take the train
here is a link with some info
Shuttle & Train info
Look it up.
You can use either Milano Cadorna or Milano Centrale stations. The former has the earliest trains and faster trains. It is also closer to the Duomo.