For resorts already open and on sale, Disney is typically selling a use year to new purchasers that begins 4 to 5 months before the date of sale but will honor use year requests unless the start month would, in its view be too far back, e.g., it may give you April at this time but maybe not Dec if you want points to start last Dec. If you got April today, your first allocation of points would be April 1, 2015. I do not know why you think April is you best choice but be aware in making the choice:
(a) Use year has nothing to do with when you can go, which is any time of year no matter which use year you have. It also has no impact on when you can call to reserve, which is always 11 months out for home resort and 7 at others.
(b) It does determine when you have an annual allotment of points , the first day of your use year, and by when they must be used for a trip, the last day of your use year, unless banked.
(c) You can bank any or all of your points into the next use year as long as you do it by the end of your 8th month of your use year, i.e., if April use year, you have until Nov 30 to bank.
(d) If you have a usual time of year that you go, it is the banking rule and the possibility of having to cancel a trip which determines your ideal use years. If you have an April use year and usually go in April, May or June, and, for example, have to cancel the trip during one of those months two months before you are to go, you still have many months during the use year to use the points or bank them. On the other hand if you usually go in March and have to cancel two months before a March trip, you will be beyond your banking date for the use year and any current use year points in that cancelled trip would need to be used by end of March. Thus, it is usually recommended when you have a usual time of year to go that you get a use year that starts shortly before that trip time, e.g., April use year is good if you usually go April, May or June, while it is not good if instead you usually go Jan to March.