I only just started using a dummy with DD at about 5 weeks, when she wanted to be attached 24/7. She is fussy with hers, either she will take it or not, if is suits her. She had bad Colic so during the day sleeps she uses it to get off to sleep and spits it when shes asleep.

At night after a feed she will go to sleep without it. If she dosent want it she will just spit it right back at ya

If it gives her comfort, I'm happy to do so, TBH I dont really like the thing but it means sometimes the difference between sleep and not, as none of the rocking, patting shhing in the world will get my DD to sleep