Congratulations on the pregnancy!
I used BG's virtually from birth, they're fine although a little wide for a newborn but not a big problem. Never had a poo leak that I can remember. They're good if your little one will be going to nursery / childminder as they're virtually foolproof for the workers, as long as the inserts still work for you - you might need to buy better one's than the microfibre ones that come with them.
Bamboo little lambs I loved, but sadly I think i need to sell - tried one on a few weeks back and bad builder's b'm... she would have been about 3 months at the time. I'm hanging on though keeping thinking that they may amazingly fit again.
The only ones we've had intermittent issues with were itti's - particularly when she was tiny. A week they'd fit, then a couple of weeks of leaking every time. It was like that for months. Now i've moved her into the mediums they're fitting perfectly.
I'd also say avoid anything with poppers when they're tiny the little gap between the poppers makes a huge difference in how much gaping you get at the waist, i felt like clara was constantly 'between poppers', so always had to either do it too tight or too loose and get leaks. Nippa's or velcro would definitely be better when they're little.