Ceremony Music

So im sitting at my computer desk staring at all this classical music that FH downloaded for me but i dont know where to being. Our ceremony starts at 2 pm. How long should you have the light music playing for, ( how long before and right up to when the ceremony actually starts) I am having wedding nightmares that my music isn't going to be done soo i wanna figure this out asap and have everything put onto a disc and ready to go for the day of...
Any suggestions??