We used a dummy from Day 1 with Parker, it was recommended by the nurses, as they said he was a dummy baby, it didn't interfere with breastfeeding, though I did use the happy dummy, the shape and the way they suck it is more like a nipple.

I used avent dummys with my first baby and had to stop using them because he would not latch on properly, but once he was about 10 weeks old, we introduced it then not a problem.

I used to be totally anti dummy past a certain age, and I think now do what you have to to get it done, in the end no child has ever had a bad reaction to a dummy, but plenty are upset and grumpy by not having one. That being said not all babies need a dummy, but maybe your little one does. You can always try it and see how it goes with the latching.

I was also going to comment on the unsettled baby, if you notice it getting worse, then it could either be reflux or colic, I just mention this because 11 days old is quite young to be starting the witching hour of colic... so it may be brewing into something else.