This could be a 9 month period. Or, it could be a 24 month period. Either way, no matter how long or short it is, overall, the two end points are the verbal commitment and first day on campus with the NLI signing somewhere in between.
That being said, from your experience, what are the major do's and don't's during this period? What can go wrong or right? What do you want to avoid and what to you want to ensure happens? What's important to watch and monitor and what is not worth worrying about?
Break it down by each segment - commit to NLI, and, then, NLI to 1st day on campus.