In answer to your first question, when you are ready! I did from week 8 with DS1 and from day 1 at home with DS2.
There are loads of routines out there. A very popular one is Save Our Sleep by Tizzie Hall. I use Gina Ford (very similiar, just UK based, Tizzie in Oz).
Establishing a routine can be hard work and you need to prepare yourself and those that support you for this. I have had great grandparents and grand parents constantly question what I am doing in the early days, but as I said to my dad, I have the long game in mind which is already paying off for DS2. My 'theory' is it takes 3 days to change something for a baby, so you have to line yourself up for 3 tough days each time to change something. I just moved DS2's dream feed back from 2230 to 2200. Done. Next thing is solids....
You need to be sure a routine will suit you and your baby. I love it because I know what I am doing at what time, and whoever looks after DS2 knows how to keep him happy too. Bonus is the sleeping through that both boys did (with a lot of work, is not easy) from 10 weeks.
Borrow some books from the library first to see what you like, then buy the one(s) you are using - so worth it, I constantly refer back to them.