At 10w I clung to a routine because I also had no idea what DD wanted, and to be honest I don't think she knew herself!
I found the Baby Whisperer EASY routine an absolute lifesaver. It's a very flexible rolling 3 hour routine (though you could make it 2 hours, or 4 hours, or whatever suits your baby). Essentially they sleep, they eat, they do some sort of activity ? which at 10w can simply be a nappy change! ? and then they sleep again. The 'Y' is for you but that doesn't entirely work at 10w
. Because it isn't telling you exact times you can just start the routine when you wake up, so it can change day by day, but I found it helped so much in guessing what DD might be crying for because I had a vague idea whether she was expecting food or sleep, and also because nap times were every x hours (sorry, can't remember exactly but probably every 1.5/2hrs at 10w?) it helped me start to learn her tired cues, which were never as obvious as some other babies were.
As for starting, I just got up one day and tried to follow it! I also had introduced a proper bedtime routine by 10w, which really was far too early for DD to understand but I felt as though it helped all of us with some structure to our day. Which really was my problem ? I was floundering completely without any vague structure at all and felt much more in control when I could think "well, she woke up at 8 and had a bottle so its nearly 11, it's probably time for another bottle now." It helped me to learn what her different cries were for different upsets. And I could see that DD preferred it, as it gradually pre-empted a lot of the meltdowns for food or sleep.
Also, on the sleep front, I found it easier to just accept that DD wanted to sleep on me or in her pushchair and gave up feeling 'trapped' beneath her. I just curled up with a book or the TV and let her sleep, or went out for a long walk, and I found that once I had accepted this it took a lot of my stress away. On a vague routine she did actually start napping better, and she had been a terrible napper beforehand.
Obviously routines are completely a personal choice and they either suit your baby or they don't, but if you feel a bit lost it might help to try one and see if it does suit you and your DD?