I have always been the DIY type, so I refused to take lessons and learned completely on my own. First day, I ate shit so many times I almost gave up. By the end of the second day, I learned how to stop, but was still falling a lot. The third day, I began to grasp the art of linking turns. By the fourth day, I was able to go down a blue (still relatively slowly). This was during a four day vacation in Canada.
Despite, what many people will say I believe it is possible to learn how to snowboard just as well without lessons. It may just take a little longer. Also, you HAVE to commit. It is so tempting to give up after the first day and then it suddenly just clicks. Good luck