I like how you said you were going to cast "4 Chaos Bolts instantly"
But seriously you don't want to use an Ember as soon as you get it, but you don't necessarily need to wait for 4 Embers either.
You have to wait for your buffs (Dark Soul, trinkets...) to use them, but you will generate more than 4 Embers between two Dark Souls, so you have to use some before, cleverly. I suppose Brusalk's video (
http://www.mmo-champion.com/threads/...ips-and-Tricks) covers this matter as it isn't all that simple, check it out.
@Apero: I will try to upload one on WM.