Either scenario: sitd & hand quilting or sitd & later quilting other areas will work. Combining machine & hand quilting is a good way to go. You may not even have to hoop for the hand quilting portion. If you return to the quilt and add machine quilting after it's done, just don't make the additional quilting too too dense as that may distort the quilt. As long as you have followed the batting requirements, you will be fine.