Hi Boss (Name )
Subject (Requesting to take vacation )
This is X (your name + Designation) wish to inform you that I am looking forward to go on vacation for 8 days starting from 15th April, 2018 to 22nd April, 2018.
To the best of my knowledge and belief, I have taken utmost care of finishing all the assigned tasks well in advance. However, considering , sufficient amount of days are still left, kindly let me know , if there is any assignment which needs to be prioritised.
I will be highly thankful to you, if you oblige