use year is when you "use" your pts for a stay. nothing at all to do with when you book. (lots of people get it confused at first.)
if my use year is oct, then i can use my 2014 use year allocation for stays from oct 1, 2014 to sept 30, 2015. those are current UY pts even if i call on nov 1, 2013 to book oct 1, 2014. (and i can call on nov 1, 2013 to book oct 1, 2014 based on my home resort only - and when you stop to think about it, you'll notice that nov 1, 2013 is 11 months ahead of oct 1, 2014 whether your UY is oct or feb...)
and you always have access to banked prior UY pts (if you have any) plus current UY pts plus borrowed pts from the next UY (if you need them). so if i called on nov 1, 2013 to book oct 1, 2014, i can even use pts from my 2015 UY if i need to. but throw out the calendar because it's all based on when your UY starts and ends.
the benefit of traveling early in your UY is that if you need to cancel, you will have more options. if you never cancel, UY month will rarely make much difference.
you may want to bookmark this for future reference:
http://www.disboards.com/showthread.php?t=1942668
edited to add: BTW, if you are locked in for june trips, a june UY is ideal. (there actually is not a may UY.) but if you might travel in late may sometimes, then an april UY might be better. ideally, you never want to travel in the last 3 months of your UY as that is past the time your banking window closes and will limit you if you have to cancel.