The combination of the preposition in and a noun in the ablative is an example of a “prepositional phrase.” (The word in is just one of many prepositions, and the majority require that the noun is in the accusative, or “take the accusative,” as it is called. See an overview here.)
The ablative has many other uses, and there is no place for “the one ablative” in a sentence. You really seem to be asking where to put a prepositional phrase.
The answer is that there is no fixed rule. All variants you offered are correct.
My impression is that prepositional phrases that have adverbial character tend to be near the verb, usually before. Direct objects, if there are any, may or may not come in between, e.g.
Datames primum experiri voluit, ut sine armis propinquum ad officium reduceret.
Datames first wanted to see if he could lead his relative back to his duty without arms (i.e., take him to order without resorting to armed conflict).
Here you have:
- sine armis (without arms): prepositional phrase with ablative
- propinquum (relative): direct object
- ad officium (to duty): prepositional phrase with accusative
- reduceret (lead back): verb
In particular, I think it makes sense to have ad officium right next to the verb, because it is integral to the meaning, whereas sine armis adds a qualification.
Artaxerxes Datamen ad exercitum misit.
Artaxerxes sent Datames to the army.
(subject – object – prep-phrase – verb), whereas:
Datames se ad Artaxerxen legatos missurum dixit.
Datames said he would send legates to Artaxerxes.
(subject – prep-phrase – object – verb; both examples, like all others in this answer, only slightly modified, from the same text, “Datames” by Cornelius Nepos.)
Note that there may be overriding considerations, e.g. if the prepositional phrase contains a relative pronoun, it will stand at the start of your clause, e.g.
saltum, in quo Ciliciae portae sunt sitae
the mountain range, in which the Cilician passes are situated
Also, parts of the sentence are often put at the front to emphasize them. Also note that parts can occur in the middle of other parts, e.g.
cum ab amico nullas vereretur insidias
when from his friend he feared no ambush
Here we have:
- ab amico (from his friend): prepositional phrase with ablative
- nullas insidias (no ambush): direct object, rudely interrupted by
- vereretur (feared): verb
But it gets even wilder:
Datames primum militum in numero fuit apud Artaxerxen eorum, qui regiam tuebantur.
Datames at first was among the number of those soldiers at the court of Artaxerxes who guarded the palace.
Note the two prepositional phrases:
- apud Artaxerxen (at Artaxerxes' place; A. was the king of Persia, so let's say “court”): prepositional phrase with accusative
- in numero eorum militum, qui … (among the number of those soldiers, who …): prepositional phrase with ablative
- fuit (was): verb
Here you have two interlocked prepositional phrases. But then again, so you do in English, at least in my translation, which I hope does not sound too stilted.
I bring these examples not to confuse you, but to illustrate that Latin word order gives the writer great freedoms. What you can do in a given situation, and to what effect, is something you can best learn by doing lots of reading.