How far in the future before we can colonise other planets within the milky way?

Maybe sooner than we think, we have mastered the science of heavier than air flight in less than 100 years, science waits for no one. Science is almost like a force of nature it continues even if we are ready for it or not, look at the atomic bomb we were not ready for such an advanced weapon at the time and look what happened(Hiroshima & Nagasaki) before we know it we will break the light speed barrier and move forward even if we are not ready, that is human nature.