When do you first see hidan and kakuzu in the anime?

Hidan Is First Seen In Naruto Shippuden Episode 10 Only In Hologram.

Hidan is Seen Again In Episode 71 In Person.

Kakuzu:

Naruto Episode 135 (Hologram)

Naruto Shippuden Episode 10 (Hologram)

Naruto Shippuden Episode 71 (In Person)

The Only Reason Hidan Wasn't Mentioned In Naruto Episode 135 Is Because He Wasn't In "Akatsuki" Yet.