On gimp, you right click your layer, and hit "edit layer attributes". Rename it *layer name* (100ms) <- the 100ms in the parentheses is the time that the layer stays there. So basically if I was doing like 2 blinks in rapid succession, I would do it open (1500ms), closed (150ms), open (125ms), closed (120ms) and then it would repeat the image. 100ms = 1 second I believe... I could be wrong, idk. Hope I helped..