services in boot process start base on number that their link have in runlevel folder. you can change their number to lower number to change its starting order. but be careful to don't make it so lower that it starts before its dependency services like networking.
you can find those runlevel folders in one of these addressees :
The runlevel-specific scripts are stored in /etc/rc.d/rc?.d, /etc/init.d/rc?.d, /etc/rc?.d,
? is runlevel number.