Why is "in the name of Jesus Christ" usually used at the end? In the scriptures, a phrase such as "in the name of the Lord" or "in the name of Jesus" is typically used at the beginning of statements, especially commands. In our day, I notice that most of our prayers, for instance, end "in Jesus' name" or "in the name of Jesus Christ." By way of another example, it seems that even most special Priesthood blessings by Latter-day Saints end with such a phrase, instead of starting with it.

Is there significance in the reversal of the placement of this phrase? Does the meaning change whether at the beginning or end?

(Sometimes I think when we say a prayer and end it with that phrase, it tends to get lost behind the other words, or is said quickly as a part of just ending the prayer, instead of carrying the meaning of praying in the Lord's name, which is why I'm asking this question.)
The answer to your question is in several Scriptures. 

In the book of Matthew He told us first of all that we should pray directly to the Father, and not for rewards here on Earth.

Matthew 6:5 through 7 KJV


  5  And when thou prayest, thou shalt not be as the hypocrites are: for they love to pray standing in the synagogues and in the corners of the streets, that they may be seen of men. Verily I say unto you, They have their reward. 
  
  6  But thou, when thou prayest, enter into thy closet, and when thou hast shut thy door, pray to thy Father which is in secret; and thy Father which seeth in secret shall reward thee openly. 
  
  7  But when ye pray, use not vain repetitions, as the heathen do: for they think that they shall be heard for their much speaking.


Then Jesus taught his disciples (which of course includes us) in the model prayer:

Matthew 6:9 through 15 KJV


  9  After this manner therefore pray ye: Our Father which art in heaven, Hallowed be thy name. 
  
  10  Thy kingdom come. Thy will be done in earth, as it is in heaven.
  
  11  Give us this day our daily bread. 
  
  12  And forgive us our debts, as we forgive our debtors. 
  
  13  And lead us not into temptation, but deliver us from evil: For thine is the kingdom, and the power, and the glory, for ever. Amen.
  
  14  For if ye forgive men their trespasses, your heavenly Father will also forgive you: 
  
  15  But if ye forgive not men their trespasses, neither will your Father forgive your trespasses.


This was given as an outline and not meant to be recited word for word, but even if you recite it word for word, what matters is your intent; and so praying the "Lord's Prayer" in not in any way sacrilegious as long as your intent is right.

He went on to say that we need to pray knowing that God has the power to grant our every wish, and that He will grant them in accordance with His plans for us.

Matthew 21:22  KJV


  And all things, whatsoever ye shall ask in prayer, believing, ye shall receive. 


John 14:13 and 14 KJV


  13  And whatsoever ye shall ask in my name, that will I do, that the Father may be glorified in the Son. 
  
  14  If ye shall ask any thing in my name, I will do it.


Finally He tells us that if we expect him to grant our request we must continue in his word, and be the best Christian we know how to be.

John 15:7  KJV 


  If ye abide in me, and my words abide in you, ye shall ask what ye will, and it shall be done unto you.


It really doesn't matter when you acknowledge Jesus Authority, either before or after, but it does matter that you acknowledge it.