Singapore yanna plan karan innawa end of this year..danata hithn inna date ekata ticket ekak pre book karanna bari wewida salli gewanne nathuwa?(date eka issarahata wenas wennath puluwna nisa)
You probably could.
But you won't be able to hold your ticket for more than 3 days. (if I'm not mistaken)
As ticket price varies from day to day, you cannot hold it for the same price.
Without payment you cant...
with payment some airlines offered flexible dates option, that means you can change date one or 2 times and ticket price is high than normal