I've had both knees done. 20 years ago what you asked about as reasonable was. Three years ago I was off work for a week (that one was bilateral) lots of swelling and pain and then more or less back to normal in a month. The bike helps a lot. Most days I don't even think about my knees anymore. Don't rush it and give yourself time to heal, comfortably.
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It's all downhill from here. Except the parts that are uphill.