My son slept through the night from 12 weeks. He self settled. It may have been luck or it may have been because he was put to bed with a dummy. Not sure. He was a very unsettled baby in the SCN until he had a dummy & then he was a placid baby from that moment on.

Whenever I've had trouble settling him I usually give him a bottle & put his Leap Tad on the night time music mode for 10 minutes. This almost always works.

Not sure if you are using bottles or a dummy but if they aren't to your taste I would certainly suggest using music. It's far easier than singing.....there's only so many times you can sing Twinkle Twinkle (or whatever it is you sing) before you get sick of it