^This. what ur asking makes no sense
Unless you use common f^cking sense and realize the OP is referring to the "Bijuu Mode" we saw Ashura use during Hagoromo's story.
And to all the other morons respond with essentially the same "Bijuu Mode is a downgrade /faceplam." I swear, you sweaty neckbeards wait at your keyboards for some small technicality you can misconstrue into a straw man for your "/thread" post.
Answer to OP: We'll see it when the fight gets more serious. Right now, Naruto is stalling, and he knows that big techniques are less effective than distractions/taijutsu. However, when Sasuke gets back, and can lend support, Naruto might decide it's a better time to maximize his power output. Basically, that "Bijuu Mode" will be Naruto's strongest form.