arduino timer

Dear all, I am trying to make a photo timer. I need to control the action of four relays. They have to act sequentially after Arduino reads a start signal from a push button or a sensor in a digital in. In the circuit four digital outs control 5v ins of four relays. I want to insert different millisecond delays for the actions. When done this, I wish to write a form with Processing to change easily via serial the millisecond values. I need an indication to start..... Maybe there is something already made..... :) But I'd like do reach it by myself and some help to learn something new.

Thanks a lot,