The land portion of each of our four Alaska trips have been four or five days and in each case, we did the land first then cruised south. At the time of all of these trips, we were still working and had significant time constraints. The first trip, 30+ years ago, was selected by our travel advisor and was independent of the cruise line (the cruise line is long defunct). The last three have been Princess cruise tours. There has been discussion about advance scheduling. Two of our three Princess itineraries were booked essentially when the itineraries were released to assure cabin selection.
As another person pointed out, the planning process is fun - enjoy!