For time adverbs, are particles instead of commas used in official (legal) writing?

Even though yesterday is not an adverb, we say:

I played golf yesterday.

only because the preposition, on, is dropped before yesterday. In that on yesterday becomes a prepositional phrase that modifies played:

I played golf (on) yesterday.

That preposition dropping is a rule. What about Japanese sentences like:

昨日、ゴルフやった。

Grammatically, is there really a particle after 昨日 such as:

昨日 (では) ゴルフやった。
昨日 (に) ゴルフやった。

In speaking, you pause instead of saying the particle, but in official writing, are those possible particles after 昨日 written (instead of a comma)?

Of course, this is not limited to just 昨日 such as:

毎日、日本語を練習しています.
先週月曜日、出張した。
など...

In English legal contracts, every last preposition and comma are triple checked because they can make such a huge difference in any sort of dispute.

Now, Japanese commas seem to be void of specificity and thus open to "interpretation" by the counterparties / judge / arbiter, right? With big $ on the line, the counterparties must specify exactly what they are agreeing to, and you can't do that with commas???

Answer

No, you won't see any case particle after following words, official or not, as long as they're used to indicate the time when the sentence takes place on/in, because they are completely adverbial in this usage.

• 昨日, 今日, 明日 etc.


• 先週, 今週, 来週 etc.


• 先月, 今月, 来月 etc.


• 前期, 今期, 来期 etc.


• 去年, 今年, 来年 etc.


• 今朝, 明朝, 昨晩, 今晩, 今夜 etc.

6時に荷物が届きそうだ。
夕方（に）荷物が届きそうだ。

今晩（× に）荷物が届きそうだ。
今日（× に）荷物が届きそうだ。
今週（× に）荷物が届きそうだ。

Of course, if you use those words in other ways, you must put right particles.

今日で仕事が終わる。 (by today)
今日にも荷物が届きそうだ。 (any day now)
今日（も／は）荷物が届きそうだ。 (particles other than case aren't affected)