Huge congratulations on your wonderful news!!!
Many years ago we adopted a six month old baby, having previously adopted her toddler brothers. I think so much depends on how you and the current foster carers work together, at what is an emotional time for both families. I remember we spent a week visiting the foster home to see the baby, doing slightly more as regards her care during each visit. We took one of her brothers with us each time to allow them to be introduced. The foster carer then visited our home with the baby, when again we would do a little more for her.
I also recall following the foster carer's routine for the baby, even if it was something I would personally not have done that way - obviously use the same milk formula/food/nappies for a while. Two little tricks that seemed to work. We left something behind (a jumper as I remember) that was impregnanted with our smell, that the baby slept with in the foster home - then once she came to us. she had teddies from the foster home that had their smell on them. That really seemed to help. I was so desperate to buy so many new clothes/toys and so on, but really it was better for her to play/wear her old familiar things for a while and introduce other things gradually.
We were always very strongly advised not to introduce our new baby to others for a few weeks or allow others to cuddle/feed her. I did intend to follow that but seeing the joy on our parent's faces when meeting the new addition, we threw that idea out of the window straight away! I am glad we did now, as she always had a wonderful relationship with her new grandparents, and we certainly never had any of the difficulties the SW had warned us of. Maybe we just got lucky, but really there was never any problem.
On the actual day the baby comes to live with you permenantly, I think I would recommend 'hand over' to be quick. It will be so emotional for everyone (and now I am a foster carer I realise how difficult it is from their side too) so I really think dragging that day out would be a mistake.
I wish you good luck on all the wonderful and exciting times to come, and hope you have a wonderful life together!