They really don't
I predict there will be an announcement shortly before Easter that her recuperation has gone as planned and she will be resuming duties as expected after Easter (and from that announcement, they'll start putting things in her diary)
Then she'll be seen for the first time on Easter Sunday at church (following which all the chuntering about how she looks will settle down)
Then I think she'll do an early engagement announcing she's taking up a patronage for whichever major charity represents the condition she's had. That will be the time she talks about her illness (one-off - because after that, it'll be about showcasing their work, not talking about herself). That will be when she thanks for cards and the public good wishes, and how she appreciated the undisturbed time to recover.
And in a further couple of months, we'll look back and wonder why so many people got sucked in to a collective folly of needing updates, wanting pix of the DC doing normal things like going to school (which would have to be pap shots, so not a good idea), wanting them to act on the tabloid demands for information.