Hi there and welcome
I found with both mine that 11-12 weeks was a great time to encourage some self-settling. Not so young that they really just need that closeness and help, but not so old that they have firmly entrenched props which are tough to sort out. Around 4 months there is a bit of development leap - some people describe a sleep regression - which for some is when the effects of props can become much more apparent. But you can go gently and take things slowly at a pace you are both comfortable with
Just before I make some suggestions though - is there any chance your LO has anything like reflux which could be contributing to unsettled sleeping? Is he happy to lie on his back when it's not sleep time? Does he always prefer to be upright for sleeping? How often is he feeding and do you think it's always a good feed, or is it snacking/comfort feeding at times? Is he vomiting or bringing back a lot of milk? Or particularly gassy?
If you're happy none of that applies, what I'd suggest is coming up with a little wind down that incorporates some walking, rocking and singing (I'd probably avoid the nursing if you can as that can be tricky to un-do later) and then get him to a point of being nicely drowsy. Keep up a nice rhythmic pat or rub whilst you are holding him (my DS liked a head rub and a hand on his tummy) and then when he is sleepy but not quite all the way there, put him down and continue the head rub/pat/whatever in his crib until he goes off to sleep. You can start small, maybe one nap a day (first one is often easiest) and gradually over time do a bit less in your arms and a bit more in the crib. Then extend it to more naps if you wish, eventually aiming towards a winddown where he goes into the crib fully awake and settles himself.
When I was doing this with DS I found it helpful to keep a couple of things in mind - first to 'do the minimum', that is, not offering more help than needed, and second to remember that my job was not so much to 'put' him to sleep, but to 'allow' him to go to sleep with me there for reassurance if he needed. Keeping the long-term in mind and celebrating small successes too was helpful!
The other thing that will help is making sure you know what a typical awake time for babies of this age is. I would have a look here and for 11 weeks I would probably be aiming to start winddown after an hour or so of awake time, aiming to have him in the crib by around 1h15 or so before he gets OT. This link is really useful -
Average A times- BOOKMARK ME! . Often that really distressed worked up crying can happen when OT sets in so if you can stay a bit ahead, it might make things easier.
What do you think?