I think the bassinet attachment was on special for $80 at target (or something similar) when I got ours. I used it from the the first day we bought DS home. We got lots of use out of bassinet, however DS was a month early so he was only 2.6 KG (5pd 12) so he fit in it comfortably until 5 months, most people I know have only used their bassinet attachment for a maximum of 3 months. He was way too little for the pram seat at first, and when he did start using it, I put a flat pillow in it to cushion him so he wouldn't roll from side to side hehehehe.
Next time I am planning to get the car seat carrier attachment instead - which target actually have on special for an additional $199. Despite the cost I think it will be worth is as DS would wake when we would transfer him to and from the traditional car seat. With this attachment, the carrier clips into a car seat base so you can take the whole thing out baby and all and clip it onto the pram frame so you don't disturb bubs - brilliant!!, I wish I'd had it with DS as I think it would be slightly more useful than the bassinet attachment. However having said that I did like that you could lay baby nice and flat in the bassinet - much better for their spines etc if you spend lots of time out and about - both are awesome, I just guess it depends on what would suit your lifestyle more.
I must say I love this pram though, its so lightweight and a dream to push around. I bought a jolly jumper pram caddy (google it) from baby bunting for $15 to attach to the handles so I had cup holders and a little zip pocket for phone and keys etc

HTH Belle - GL on your pregnancy