diff --git a/.github/workflows/scheduled-slack-glossary-maintainers.yaml b/.github/workflows/scheduled-slack-glossary-maintainers.yaml
index 164c11502..bccf9ac2d 100644
--- a/.github/workflows/scheduled-slack-glossary-maintainers.yaml
+++ b/.github/workflows/scheduled-slack-glossary-maintainers.yaml
@@ -3,10 +3,12 @@ name: "Slack scheduled message: CNCF Glossary WG reminder"
 on:
   workflow_dispatch:
   schedule:
-    # 4th Thursday is always the 22nd–28th, on weekday 4 (Thursday)
-    # Every 2 months starting January:  Jan, Mar, May, Jul, Sep, Nov
-    # 00:00 UTC
-    - cron: "0 0 22-28 1,3,5,7,9,11 4"
+    # The meeting is on the 4th Thursday of every 2nd month (Jan, Mar, May, Jul,
+    # Sep, Nov) at 00:00 UTC. The 4th Thursday is always the 22nd–28th.
+    # cron ORs day-of-month and day-of-week when both are restricted, so a
+    # weekday here would add runs instead of narrowing them; the guard step
+    # below is what selects the Thursday.
+    - cron: "0 0 22-28 1,3,5,7,9,11 *"
 
 permissions:
   contents: none
@@ -16,16 +18,22 @@ jobs:
     if: github.repository == 'cncf/automation'
     runs-on: ubuntu-latest
     steps:
-      - name:  "Guard: only run on 4th Thursday"
+      - name: "Guard: only run on 4th Thursday"
+        id: guard
         shell: bash
         run: |
           day_of_week=$(date -u +%u)  # 1=Mon, 4=Thu, 7=Sun
-          day_of_month=$(date -u +%d)
+          day_of_month=$((10#$(date -u +%d)))  # base 10 so 08/09 are not read as octal
           if [[ "$day_of_week" != "4" || "$day_of_month" -lt 22 || "$day_of_month" -gt 28 ]]; then
-            echo "Not the 4th Thursday (day_of_week=$day_of_week, day_of_month=$day_of_month). Exiting."
-            exit 0
+            echo "Not the 4th Thursday (day_of_week=$day_of_week, day_of_month=$day_of_month). Skipping."
+            echo "post=false" >> "$GITHUB_OUTPUT"
+          else
+            echo "post=true" >> "$GITHUB_OUTPUT"
           fi
       - name: Post message to Slack
+        # exit 0 in the guard only ends that step; the job keeps going. Gate on
+        # the guard's output instead. Manual runs always post.
+        if: github.event_name == 'workflow_dispatch' || steps.guard.outputs.post == 'true'
         uses: rtCamp/action-slack-notify@33ca3be66c6f378fe1610fd1d5258632dbed5e58 # v2.4.0
         env:
           SLACK_ICON: https://github.com/cncf.png?size=48