You're not that kind of karma that just spits out her Q with ult whenever possible.
The trick to getting early game dominance on bot lane: Let the enemy think they have upper hand, you need great cooperation with you adc. Mostly you'll be in the front line, gettin harassed, and don't be afraid of it. The enemy most likely become greedy, and whenever you are(or at least they think you are) out of position, they're going to engage, and thats where you're gonna use your ult on W, shielding you, and as your root unlocks, you Q him(in case he needs a couple more hits from your adc, otherwise, let him get the kill).
This little trick almost always leads to a fed adc on your team, ending in an easy win.

Now your primary role is to support your team wherever you can. You should accompany your adc almost everywhere. Best to group up with whole team and pushing one lane, but thats variable on enemy team's and your team's tactics. Depending on your team setup, enemy team setup and quite some other things that you'll feel in the current situation, whether or not, you'll end up initiating.
If you are, obviously, use your ult with W, otherwise with E, here it doesn't really matter if you die, you give time and space for your team to kill high value targets. Your ult+E+locket+reverie gives so much dominance in a teamfight, that your team can easily position themselves. In case you used you ult to heal, it gives your team enough time to do so, for you'll be focused by 2-3 enemy.