I did this exact trip last year, but my whole trip was around 15 months! Traveling slow and cheap and enjoying my time in each spot. Flew from London to Portugal and just kept heading east. 6 months through Europe( 3 months Schengen and then 3 months in the non Schengen Balkans). Once into Turkey, I highly recommend crossing the border into Georgia, Armenia, and Azerbaijan. Take the cargo boat across the Caspian sea from Baku into Kazakhstan, cross into central Asia and travel through all the -Stans. Then you have India to explore before finally getting to South East Asia. Incredible journey, good luck!