@Nilton_Mendes in co-term expiry organisations (the only option until recently) the license starts from the date it is delivered, there is no such thing as activation.
What you should have done (had you known) was to cancel the license and re-order now, however what I would now do in your position is speak to the reseller and ask that if you order a new license that he gets some extra time added to cover the lost period. I doubt you'll get the whole 3 years but it's definitely worth asking, remember that the longer you order, the more free years you get, sometimes up to order 5 and get 10.