To be accurate,
a perfect "That Jutsu" was referred to Bijuudama
but Naruto never achieved the perfect during that time when "that jutsu" was used many times in the manga.
He reached up to "Odama Rasengan" And increasing the size of the Rasengan pulled Naruto close to the Kyuubi. ( you can see his eyes turning to Kyuubi's )
To perfect, "that jutsu" Jiraiya trained Naruto to control the Kyuubi. That's why he warned Naruto not to use "That jutsu" otherwise Naruto might lose control over himself.
Killer Bee helped Naruto to master "that jutsu"
We all know Naruto has no other jutsu apart from Shadow clone, Transformation, Sexy, Rasengan variations and Rasenshuriken.
Out of these Rasenshuriken has nothing to do with "that jutsu" Also Shadow clone, transformation and Sexy jutsu are normal jutsus.
Only left is to take Rasengan at further level without adding any other elements.
When Naruto tried to make Rasengan after taking over Kyuubi's chakra, Killer Bee noticed that it's Bijuudama.
That is the moment when the mentioning of "That jutsu" in the manga stopped. Because Minato and Jiraiya wanted Naruto to master Bijuudama because he(Minato) sealed Kyuubi inside Naruto.