Hi! There is an old saying that I never truly knew the meaning of until I had my first daughter "If it ain't broke, don't fix it".
You have a dream come true newborn - my first daughter was collicy (sp?) thru 9 months and that was a complete nightmare. My seconds was a godsend, she would nap & was sleeping from 8PM-5AM just after 3 months. It has been the experience of many that once you go messing with their sleep schedules, it is so difficult to get them back on track.
We moved into our new house when my youngest was 8 months and had to then go through the whole sleep battle all over again. I know it's hard to gauge things around our newborns, but sometimes we really have to think long & hard when we pick our battles.
I'm sure you will get tons of views, suggestions, etc. Many people do the whole sleep train thing. We tried the Ferber method with our oldest she would vomit while in her crib because she would be crying so hard so we never even tried that again. But my cousin did it w/both of her children & it worked wonderfully. I guess you just never know! My oldest is 11 & I'm still trying to figure things out! Good luck!