Ferdy, if ypu're someone who feels like they would like/need a routine then by all means go for it... despite lots of people thinking I was a psycho, it just became very apparent in the early weeks that I wasn't going to survive with my sanity intact at all without some kind of structure/routine in my day. You need to think about whether this is you. Don't take on a routine if you're happy as you are/content to go with the flow etc. because someone has made you feel as if you ought to.
That said, if you have decided it's the way you want to go, just pick a book and go with it - they all seem to go along similar lines in any case, you may find.
BUT, don't get all bent out of shape when things go awry (and at 5 weeks they invariably will, if my experience is anything to go by), if/when it goes pear shape, just try and wriggle things round until the next viable time slot.
This, I think, is the key to not driving yourself batty with those books - understanding that your LO hasn't read them, and will want/need what he/she needs when he/she needs it and you won't have a lot of choice but to comply!
It won't fall into place immediately, but it will eventually... take it a day at a time.
By the way, if something doesn't work for you, you can always switch - we started with the baby whisperer, but the daytime sleep patterns were all wrong for my DD, so we switched to Gina [ducks and whispers] which worked much better for us...
The early weeks are total chaos though, and whatever you do, it WILL get easier.
Good luck!
db
xx