If you're a reservist your unit should be contacting you with the updated N426 instructions and require you to acknowledge & receipt. This is due to the Kirwa lawsuit where they're forced to comply on getting the service period signed lol. They went from ignoring these requests to expediting.

Even if you already have a pending N400, I would do it anyways, the legal advice is that down the line (in the naturalization interview or otherwise) they may request another N426 which needs an O6 certification.