From your last post, I personally think knowing the sex soon will help you guys although it will be bloody hard regardless of the sex. I think being able to give the baby a name will bring it to life, IYKWIM, and quite possibly allow you to start referring to the nursery and the nursery goods as it's room and stuff.

Can you afford new bedding and accessories for the new baby? Maybe it would help to put Jack's away, when you're ready of course, and keep it special, always his. The fresh accessories in the nursery may help to make it the new baby's room. I hope that makes sense, I'm obviously not speaking from experience but I know I want this baby to have it's own 'stuff' and be able to put it's stamp on the nursery even if it is another DD for us. KWIM?