Students can successfully transition to models like ours from diverse backgrounds including private school, public school, and homeschool. Any student who is at or above grade level in their current school should be able to transition successfully to NCC. The first few weeks of our year include some review and we also gradually increase the amount of work for the at-home days during the first weeks of the semester. Some memory work such as the English phonograms and the History Timeline begins in the early grades and is repeated each year, so students can learn these items beginning in any grade. Latin curriculum similarly has an entry point at each grade. New students will be placed into a Latin course that is suitable for beginners.
In terms of transitioning from homeschool, the routine for at-home days may remain similar to what you have done previously. While parents follow the NCC curriculum, because the instruction is at home 2-3 days a week, many of the aspects and benefits of homeschooling are completely preserved.