I have been using the BG 3.0's on my 20 month old since he was 2 months old. He was a big baby, so we could have switched sooner. We were so glad to switch from the prefolds because he moves a lot on the diaper table, and we loved how fast the BG are.
I don't know if you have decided between snaps and velcro, but here's my take. The velcro is nice because it's much faster to put on, and as I mentioned, he moves around a lot. Also, it's easier to get an exact fit. However, after 20 months, the laundry tabs have worn out, so the velcro comes off during the wash and we end up with this giant chain of diapers. CottonBabies sent me repair packs for free, but it's hard to find the time to sew. The 4.0's (we have one) seem to have better laundry tabs that should last longer, but still the velcro degrades over time.
We do have a smell problem with all of our diapers, but we love the BG the most out of the 8 brands we have.
Good luck, and congrats on your coming joy!