Interesting information indeed. So lets approach this differently.

Suppose I write {jaj veb, vIghro' tIQ wIHaH'eghmoH}, for "next day we bathe the ancient cat".

The first question is "is this ungrammatical ?", and the second question is "what is the {jaj veb} if not a timestamp ?".

I don't think its ungrammatical, and seemingly/apparently {jaj veb} functions as a timestamp.

The only problem is, we don't know which day this {jaj veb} refers to.

It is a time stamp, and it's perfectly grammatical; it's just doesn't refer to a specific next day.

When you say jaj veb in Klingon or the next day in English, you're speaking deictically: the meaning of your expression is based on some already-established context. In this case, it might be directions for honoring a cat, in which case the context is that you have already begun the honoring process, and the next step takes place on the next day. You haven't specified which day on a timeline this is happening; it's not "March 26" or anything; it's just the day after the day you were already talking about.

-- 
SuStel
http://trimboli.name