If you remove the third inner plug (with the small holes to fill thru) to fill these cartomizers, how far do you fill them up? All the up to the bottom of the cup, etc.? The instructions say to fill these with about 1ml of fluid, but unfortunately I am using a syringe with all the markings rubbed off. I was hoping to more accurately fill these by removing that third cap, but now I'm just not sure how far to fill them up. Thanks!