As with everything else, YMMV (Your Mileage May Vary). Some people are walking around a day or two after surgery, while others may require more time to heal. I had a breast augmentation performed at the same time as my bottom surgery. The BA was initially the more uncomfortable of the two procedures, and it had my full attention for the first week or so.
I'm not sure that there is any way to prepare for the abrupt visual change in your anatomy. There can also be a lot of bruising. After surgery, the first few times you dilate can be uncomfortable and disconcerting. It takes time for the swelling to subside, and it may be a few months before you become completely comfortable with your new designer amusement park.
Based on the research I did before my surgery, Dr. McGinn is one of the best. She is also featured in a film called 'Trans', which has some good information.
If you have any personal questions, send me a PM.
Love always -- Jessica Rose