Voldemort já decidiu sobre o que Horcruxes ele deveria fazer?

Voldemort escolheu objetos que ele achava que eram importantes o suficiente para a honra, e isso o ligava a sua infância em Hogwarts e seus ancestrais. Dumbledore explica isso em Half Blood Prince.

"His pride, his belief in his own superiority, his determination to carve for himself a startling place in magical history; these things suggest to me that Voldemort would have chosen his Horcruxes with some care, favoring objects worthy of the honour.”

“The diary wasn’t that special.”

“The diary, as you have said yourself, was proof that he was the Heir of Slytherin; I am sure that Voldemort considered it of stupendous importance.”

Ele continua especulando que Voldemort quer relíquias das quatro casas para completar sua coleção.

“I can only guess,” said Dumbledore. “For the reasons I have already given, I believe that Lord Voldemort would prefer objects that, in themselves, have a certain grandeur. I have therefore trawled back through Voldemort’s past to see if I can find evidence that such artifacts have disappeared around him.”

“The locket!” said Harry loudly. “Hufflepuff’s cup!”

“Yes,” said Dumbledore, smiling, “I would be prepared to bet — perhaps not my other hand — but a couple of fingers, that they became Horcruxes three and four. The remaining two, assuming again that he created a total of six, are more of a problem, but I will hazard a guess that, having secured objects from Hufflepuff and Slytherin, he set out to track down objects owned by Gryffindor or Ravenclaw. Four objects from the four founders would, I am sure, have exerted a powerful pull over Voldemort’s imagination. I cannot answer for whether he ever managed to find anything of Ravenclaw’s. I am confident, however, that the only known relic of Gryffindor remains safe.”

Então, sim, Voldemort especificamente procurou as relíquias dos fundadores de Hogwarts para transformá-las em Horcruxes e conseguiu três. Ele só abandonou este plano em seu retorno, criando a Horcrux Nagini no início do Cálice de Fogo.

Voldemort sendo um órfão ficou em um orfanato trouxa durante os feriados. Ele não gostava do orfanato e chegou a olhar para Hogwarts como uma casa, assim como Harry.

“My dear boy,” said Dipper kindly, “I cannot possibly let you stay at school over the summer. Surely you want to go home for the holidays?”

“No,” said Riddle at once. “I’d much rather stay at Hogwarts than go back to that — to that —”

_{^{Harry Potter and the Chamber of Secrets, Chapter 13, The Very Secret Diary}}

Em algum momento durante seu quinto ano em Hogwarts, Voldemort soube de sua ascendência sonserina, que foi um dos fundadores de Hogwarts, e seu desejo de se associar a Hogwarts poderia ter aumentado.

Quando ele tinha dezesseis anos, ele deixou o orfanato para o qual ele retornou anualmente e partiu para encontrar seus parentes Gaunt. Ele conheceu seu tio Morfin Gaunt e ficou sabendo sobre o medalhão da Sonserina.

“Ar, he left her, and serve her right, marrying filth!” said Morfin, spitting on the floor again. “Robbed us, mind, before she ran off., where’s the locket, eh, where’s Slytherin’s locket?”

_{^{Harry Potter and the Half-Blood Prince, Chapter 17, A Sluggish Memory}}

Este poderia ter sido o ponto em que Voldemort teria pensado em procurar por todos os itens mágicos associados aos fundadores de Hogwarts. Mas acredito que a decisão final foi tomada quando ele tinha dezessete anos.

“He reached the seventh year of his schooling with, as you might have expected, top grades in every examination he had taken. All around him, his classmates were deciding which jobs they were to pursue once they had left Hogwarts. Nearly everybody expected spectacular things from Tom Riddle, prefect, Head Boy, winner of the Award for Special Services to the School. I know that several teachers, Professor Slughorn amongst them, suggested that he join the Ministry of Magic, offered to set up appointments, put him in touch with useful contacts. He refused all offers. The next thing the staff knew, Voldemort was working at Borgin and Burkes.”

“At Borgin and Burkes?” Harry repeated, stunned.

“At Borgin and Burkes,” repeated Dumbledore calmly. “I think you will see what attractions the place held for him when we have entered Hokey’s memory. But this was not Voldemort’s first choice of job. Hardly anyone knew of it at the time — I was one of the few in whom the then headmaster confided — but Voldemort first approached Professor Dippet and asked whether he could remain at Hogwarts as a teacher.”

“But he didn’t get the job, sir?”

“No, he did not. Professor Dippet told him that he was too young at eighteen, but invited him to reapply in a few years, if he still wished to teach.”

“How did you feel about that, sir?” asked Harry hesitantly.

“Deeply uneasy,” said Dumbledore. “I had advised Armando against the appointment — I did not give the reasons I have given you, for Professor Dippet was very fond of Voldemort and convinced of his honesty. But I did not want Lord Voldemort back at this school, and especially not in a position of power.”

_{^{Harry Potter and the Half-Blood Prince, Chapter 23, Horcruxes}}

Então, depois de completar sua educação em Hogwarts, Voldemort tinha dois planos:

1. Comece a ensinar em Hogwarts
2. Procure por itens mágicos associados aos fundadores de Hogwarts

Então, quando Voldemort tinha 15-16 anos, ele planejava usar itens mágicos associados ao fundador de Hogwarts. Ele decidiu seguir com seus planos quando tinha 17 anos de idade.