Update key dates

sites/main-site/src/content/events/2025/hackathon-march-2025/index.mdx

@@ -26,9 +26,13 @@ to hack with other Nextflow / nf-core enthusiasts in person!
 
 :::info{title="Key dates"}
 
--   Late December 2024: Registration opens for hosting local sites
--   Mid-late January 2025: Event registration opens for participation
--   March 24-26 2025: Hackathon
+-   **December 2024**: Registration opens for hosting local sites
+    -   _Local site registration is possible until the event starts, but it's recommended
+        to do before the in-person registration opens._
+-   **Jan 31st 2025**: Registration opens
+-   **March 9th 2025**: Local site registration closes
+    -   _Online registration will remain open until the end of the event_
+-   **March 24th - 26th 2025**: Hackathon
 
 :::
 
@@ -38,7 +42,7 @@ and [2024](/events/2024/hackathon-march-2024) (23 local sites, 466 attendees).
 
 ## Registration
 
-Registration to join the hackathon as a participant will open in late January.
+Registration to join the hackathon as a participant will open on Friday, January 31st.
 
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