I took online prerequisites starting last fall (2015) and applied for graduate schools that same semester. Some of the programs had three-year tracks, but most did not. I'm finishing up the last two courses this summer. All of the programs I applied to were okay with the fact that I'm currently in leveling courses. I just made sure to send in my transcripts as soon as they were available last semester, which ended up being before the deadline for most of the programs. I'm my opinion, I think programs like to see individuals who take the initiative to complete courses before/ while applying It certainly makes you more competitive when so many applicants have a CSD undergraduate background.