I'm not sold on D5 as a date. Most times it is used, its almost like a Trump card, like something we know but have not figured out.

God Bless the United States of America. D5. (#1401)

Why is Schneiderman's removal 'extremely' relevant? TRUST (name). These people are stupid. D5. (#1433)

Important marker. Think connections. D5. (#1743)

There is a reason why we needed to go mainstream prior to the EVIDENCE being dropped. You have more than you know. D5. (#1816)

WHY WAS THE INFORMATION ON WEINER'S LAPTOP IN THE FIRST PLACE? D5. (#1978)

Normal? PANIC. D5. (#2275)

Think DECLAS. https://www.cnn.com/2018/10/03/uk/uk-russia-cyber-attacks-intl/index.html? D5. (#2332)

Nothing to See Here… D5. RED OCTOBER. (#2333)

Do you believe in coincidences? Think D5. Panic in DC.(2498) .........................................

There is one use of D5 that does seem date related.

https://thehill.com/hilltv/rising/417761-house-gop-to-hold-hearing-into-dojs-probe-of-clinton-foundation [D]ec 5 D5 Nothing can stop what is coming.

But notice in this case there is no period after D5. After this message, the D5 is never given punctuation again