New parent here, 18 months old twins.
I've upgraded bodies, bought number of lenses, rented bunch, so here is my take:
Zooms are easier to use, but more ordinary. I'd look Tamron 17-50 2.8 (non VC), or even 28-75 2.8. Second one is meant for full frame, so I have it on Canon full frame, but also on Sony crop, and love it crop too, They're very good, not spectacular, but great use of $400-$500 for new, or about $350-$400 used
Primes are more limiting, but keepers you get with these will be something to behold. So if you're just starting, I'd suggest primes, 35,50 and 85 is what's practical on crop body. You have 40, so I'd say get 50 1.8 if you want to save a bit ($100), or 50 1.4 if you feel like spending ($350), and then get 85 1.8 ($350). You don't lose much with 50 1.8 vs 1.4, and you can spend that money on 85 1.8, so I'd start with 50 1.8 and 85 1.8.
85 1.8 is most limiting and hard to work indoors, but will give you some stunning pictures.
Rent 50 1.2 and 85 1.2, they're something else, but don't buy unless you're rich, or you catch bug. Rental in USA lensrental.com, in Canada Vistek and Headshots in major cities...
Some samples of my pics at http://babiesphotos.ca/
though this is from few different cameras...