From holding baby to sleep to letting him sleep independently?

My baby is 3 months old and I’ve been rocking him to sleep and then co-sleep as he can’t sleep long in his crib. For naps, I’ve been baby-wearing or holding him for the same reason. But I think this isn’t good and sustainable for my family’s lifestyle :( I hope he can sleep well and independently one day.

I tried the “drowsy but awake” thingy but he always get agitated. I do use the swaddle, white noise and the room is dark.

For mummies who didn’t sleep train, how old was your baby when he or she managed to fall asleep independently without you holding them? Any tips to share? :( Thank you in advance!