[hieklyintinee]

Very First Sunnah:

1) Performing Ablution (Wudhu), and doing siwaak upon waking up.

Ablution:
Bukhari ::Volume 4 :: Book 54 :: Hadith 516

Narrated Abu Huraira radhiyallahu anhu:
The Prophet said, “If anyone of you rouses from sleep and performs the ablution, he should wash his nose by putting water in it and then blowing it out thrice, because Satan has stayed in the upper part of his nose all the night.”

Siwak:
Bukhari :: Book 1 :: Volume 4 :: Hadith 246

Narrated Hudhaifah radhiyallahu anhu:

Whenever the Prophet got up at night, he used to clean his mouth with Siwak.