It is too late to cancel my order.
(What does 'it' refer to in the sentence? Is 'it' a false subject or the impersonal pronoun referring to 'the time'?)
This is another instance of "it" being used when it has no antecedent. Your questions in the parentheses can both be answered YES! It's something of an idiom, I guess ... like these:
It's hot outside today.
It's raining cats and dogs.