Prints will not center on bed

So I built a TEVO Tarantula about a month ago, and after various small prints I'm wanting to go big.
So this is where the problem begins, I have the printer all setup in Repetier Host and Sli3er with the correct measurements of the build volume, and for some reason when I slice an object and print it, the extruder homes and then moves forward about 47mm on the Y and 12mm on the X. Then it starts printing like normal. Whats more weird is that when I go to the manual control tab and move an axis manually, the same offset occurs. I've searched the settings in Sli3er and Repetier Host and have experimented with different offset types but nothing works.
I've seen other forums on this topic and cannot get an answer, so any help is greatly appreciated.

check you homeing positions in your firmware

ie

#define X_MIN_POS 0
#define Y_MIN_POS 0
#define Z_MIN_POS 0
#define X_MAX_POS 200
#define Y_MAX_POS 200
#define Z_MAX_POS 200

this needs to match your hardware
Start with the position of your endstops,
eg it look like your X axis has a endstop on the right hand side. this is a max endstop, when you home X to max, how far away is it from X0, enter this into
#define X_MAX_POS

do the same for Y, if the Y endstop is at the back this is a min endstop, if the Y endstop is at the front, this is a max endstop