Nothing in the RP is instant except Space/Time techniques.How i performed it
Sasuke starts to build his chakra, then he uses nature manipulation to transform the chakra into wind while simultaneously channeling it from hiss gut to his mouth, sasuke then opens his mouth to spew out wind while he instantly uses shape manipulation to widen the scale of the wind as it travels to hit the summoned hyena.
Advantages
It looks like its created in an instant, not only does it push back it also delivers small cuts, which will obviously cause injury.
Disadvantages
I can't really think of a disadvantage, since its pretty straight forward, only that a fire jutsu with the same scale of this wind, will be able to push it back to the user of the wind.
your counter
In a way I honestly don't think your counter would work,first this jutsu is able to push down a summon, and not just any summon but a big one, your counter are small balls of fire which explode on impact, now we can say that the fire ball hits this wind jutsu and it explodes allowing the explosion to nullify the wind jutsu, but what I think is due to the size of this wind jutsu your fire ball would only ignite it with flame and still have the now fired wind jutsu to travel at you. Even though the fire ball explodes I still have the same thought.
The Speed Rate
I rate it as fast, since everything is done from the mouth, then it would be come out as just released though a little shape manipulation but it not a bother.
(Fūton: Fūsui Ranha no Jutsu) -Wind Release: Wind Water Wild Wave Technique
Rank: B
Type: Offensive
Range: Short - Mid
Chakra cost: 20
Damage points: 40
Description: The user will first release a wave of water at the opponent, and then the user will enhance the wave's destructive capacity with wind.
So, first use a water technique B-rank or lower. Afterwords, release a gust of wind from your mouth to empower the water wave, making it travel faster and become stronger. This is best used with 2 or more people, such as an ally or clone.
-Creates clone-
I use..
(Katon: Gōka no Jutsu) - Fire Release: Hellfire Technique
Rank: A
Type: Offensive
Range: Short - Mid
Chakra cost: 30
Damage points: 60
Description: The user will manipulate their chakra and breath out from their mouth a large fireball that travels at the opponent. As it reaches the opponent it bursts into a maelstrom of fire engulfing them in flames.