You hit the nail on the head though, consistency is key. We also bath DD even now at 20 months every night. I just do the same as I do at night minus the bath.
So night time is bath, brush teeth, say goodbye to the photos in the hall (of places we visited before we got married) then get her dried, into PJ’s, into her sleeping bag. Quick cuddle where we tell her we love her and she needs to sleep now and that we will see her in the morning.
Day sleeps, we say goodbye to the photos, put her in her sleeping bag, continue with the quick cuddle etc and down she goes.
Back then I would do the same routine (though at 6 months I’d still feed her before each nap and bed time, but just a small bottle) and sit and shhhh pat until she fell asleep. 12 weeks some may argue is too young to try CC or Tizzie Halls methods (do note they are different), but the shhhh pat I was taught by child and youth health (govt agency) here in SA, so I figure the public health system wouldn’t be teaching parents to do something harmful to their babies so that’s what we did. Having said that though, again we were comfortable to do that. If you are not then don’t take on my advice, but I found it was not as gentle as cuddling (but far more effective in the long run) but not as extreme as controlled crying (but took a lot longer than controlled crying).
There were times too when we thought it was too hard and just picked her up, but that was taking 2 steps forward, 1 step back.
The first time she ever self settled at night was when DH couldn’t be bothered sitting and patting her to sleep and just put her down and left. With no crying at all she fell asleep! So we continued the same routine every night at the same time and it worked.
I think in my mind, set up a good routine / method and stick to it. It’s never the method itself that works, but the consistency of what you do. What I don’t mind about Tizzie Halls methods is that when they are younger the time to leave them is short (something like 3 minutes), if they aren’t asleep, then go back in to bub and help them get to sleep how ever you need, feed, pat, shush rock until they sleep. Lets face it you may need to take a 3 minute shower or go to the bathroom and bub will cry for that long without you. I personally think once you’ve got your timing and routine down pat, you should just try leaving your baby for a short period and see what happens. You might surprise yourself, he may fall asleep without crying as he knows you are there to come back and he also knows how to fall asleep.