Now (when it is already much too late); at this stage — implies that it's too late for the action to be effective or appropriate.
今更謝っても許されないだろう。
Even if you apologize now, you probably won't be forgiven.
今更そんなことを言われても困る。
It's no use telling me that now; it puts me in a difficult position.
今更止めると言われても契約は既に締結されている。
Saying you'll stop now is too late; the contract has already been signed.
Afresh; anew; again — used to indicate doing something over or anew, often with a nuance of reluctance or surprise given the timing.
今さらやり直しても遅いとは限らない。
It's not necessarily too late to start over now.
彼は今さら新しい言語を学び始めた。
He has started learning a new language at this stage (now).