At 6 weeks, I would think that your feeding is probably established well enough to introduce dummy. We use one for DS, but only for sleeps/if he is really upset. I don't let him just suck on it all day - because then he wouldn't babble etc & I worry that it would interfere with his speech development.

Don't stress about the eventual "weaning" off the dummy. Babies will have to give up lots of their comfort things eventually - wrapping, dummies, boobies, etc. - but when the time is right, it's not that bad. DS wanted to be wrapped for ages (until he was 9 months) - but when he decided he didn't want it anymore, the wrap was all gone within a week & he was sleeping fine. I'm presuming it will be the same with the dummy.