Eli Rhyne

I am a high-school student of the sophomore year and I have a project which is I want to make a coil gun that is 3 stages and I want all three coils to each be powered by its own capacitor. I want to specifically know how to time each coil which i would find more precise than an IR system(if i'm wrong please correct me) the coils will be about 2-1/2 to 3 inches apart(if there is a better way to space them tell me) and my projectiles will be 6 mm .89 gram steel bullets. I'm open to suggestions. I have limited funds but have access to drafting software and basic soldering and electronics skills but my knowledge is limited.