The masnűn procedure for the khatam (completion) of the Qur’ân is that when the recital of the full Qur’ân is completed then one should immediately start the reading of the next khatam.
Rasűlullâh 
always
during his recital of the Qur’ân, when arriving at Sűrah an-Nâs,
paused there, and then read Sűrah al-Fâtihah together with Alif Lâm
Mîm up to muflihűn (the first 5 âyât of Sűrah al-Baqarah),
and thereafter made the du’â.
Rasűlullâh has
said that it is very much liked by Allâh 
that
whenever the recital of the entire Qur’ân is completed then the next
re-reading is immediately commenced with and the recital then stopped at muflihűn,
after which the du’â should be made.
It is reported in several ahâdîth that Rasűlullâh has
said that the du’â at the completion of every khatam of the Qur’ân
is assured acceptance. In one hadîth it is stated that: “When a person
completes the Qur’ân, the malâ’ikah (angels) kiss him between the
eyes.” In another hadîth it is reported that, “Whosoever completes the
Qur’ân during the early hours of the day, then the malâ’ikah ask
Allâh to show mercy on such a person for the remaining of the day, and likewise
whoever completes it at the commencement of the night, the malâ’ikah
ask Allâh to show mercy on such a person for the remainder of the night.” It
is reported that Rasűlullâh has
said, “Whosoever reads the Qur’ân and then performs du’â
thereafter, then four thousand malâ’ikah will say ‘Âmeen’
upon his du’â.”
A short selection of du’âs that could be read after the completion of the Qur’ân-ul-Karîm are given as follows:
[Source: al- Qur'an. Waterval Islamic Institute]