Q also mentioned to “remember this day” 3 times in the past.

Always on January 19th of various years

It is very possible he was going to tweet in 15 minute increments, but barely missed the minute. This tweet came in at 12:46, the one prior was at 12:30, the one following at 1:00.

Or, I guess he could be doing his 15 minute signal, but intentionally shifted by 1 minute to send this coded message. We would, after all, notice the sudden inconsistency and investigate it.

Good catch!