They did try to implement it, though. Or rather they started a transformation (i.e. collectivization, de-kulakization, etc) of society that they thought was necessary for communism.
... yet it's "generous" to describe the provisional government which was dominated by socialist parties as socialist leaning?
Say what you want about Lenin, Stalin and co. (and there’s a lot to be said), they were true believers in the stuff they were selling. It’s absolutely fair to call them communist.
Stalin's position as a true believer is dubious at best.