You will need to establish some technique before we can talk about a realistic time frame at all. Even then each honer has his own pace. That said;

A workman is only as good as his tools. For totally dull, you'll want more than just the Norton 4/8k combo. That'll take forever, or at least days maybe. Moving up in grits is a great way to cut your time and if your technique is perfect and you've got a collection of stones at your disposal which are high quality and fast cutters .... an hour? I'm never so lucky though.

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