I gave Charlie a dummy around day 4, we had just gotten home from the Hosp (they wouldn't let me use it there) & I needed a rest & he wouldn't settle. Bless him, I put the dummy in & he slept for 4hrs!!! Yay.
I honestly think they know if they want it or not & when. If she is not fussing I wouldn't start with it...I used one as it was our saviour when he wouldn't sleep...the FIRST 3 MONTHS arghhhhh. But Charlie knows he doesn't want it for anything but sleep, give it to him during the day & he won't even put it in...he just plays with it & that cracks me up.