Use years are identified by the calendar year they begin in even if it has more months in a subsequent year. Thus, if you have an October use year, your Oct 2014 use year runs from Oct 1, 2014 to Sep 30, 2015.
If you have an Oct use year and a March 2015 trip then:
1. The points that are issued October 1, 2014 and expire Sep 30, 2015 are your "current" use year points for that trip (and are referred to as Oct 2014 use year points). Points issued October 2015 (the start of your Oct 2015 use year) would have to be borrowed for that March 2015 trip. If you have October 2013 use year points, they would need to be banked to use for that trip.
2. At your home resort, you can reserve 11 months out from date of arrival, 7 months out at others (that 11/7 rule is always the same regardless of your use year or trip dates). Thus, for a March 2015 trip, you can reserve home resort beginning in April 2014 excactly 11 months out from the particular arrival date, and another resort beginning in August 2014, 7 months out.
5. Points you use for the trip are determined by when you will be at WDW and not by when you call to reserve. Thus, if you call to reserve a March 2015 trip in April 2014, the "current" use year points for that trip will be the ones from your October 2014 use year that runs from Oct 1, 2014 to Sep 30, 2015.
6. You generally should not wait until 6 months out to make a reservation like you are suggesting to do by reserving in Sep 2014 for that March 2015 trip, because you could easily find that the resort and room category you want will already have been filled. Rooms can start to fill 11 months out and at 7 months, when everyone gets to reserve any resort, anything left can quickly disappear particularly if you are seeking any near park resort like BWV, BCV, BLT or VGF. Thus, I recommend you consider reserving your home resort now since it is already June 2014, 9 months out, if you want your home resort. If you want another resort, you best be prepared to do it in August exactly 7 months out and not wait until September..