The train journey from Milan to Portofino involves taking a train from Milano Centrale station to Santa Margherita Ligure station, which typically takes around 2-3 hours depending on the specific train and any connections involved. From Santa Margherita Ligure, one can then take a bus or taxi to reach Portofino in approximately 15 minutes. Overall, travelers should allocate around half a day for this journey when planning their itinerary.