it not too late..suitable time indeed..i am 27 years old..already went for first inteview sia and first stage of air asia....sia interviewed quite tough..one hour drill about basic flying principle..the sia aircraft and the flying by wire concept...the capt will provoke your judgement...and see how your defend it..

just apply via sia website..but depend on your luck..someone has waited for 4 years just for the first interview..and mine was 2 month..