Since you have an October use year:
Your 2005 points are good for stays that occur between 10/1/3005 and 9/30/2006. If you bank them, they become valid for stays that occur between 10/1/2006 and 9/30/2007.
With an October use year, you may bank up to 100% of your total annual alltoment as long as you do it before the end of the following March.
You may bank up to 50% of your total annual allotment if you do it prior to the end of June and up to 25% if you do it before the end of the July. No banking is allowed in August and September if you have an October use year.
Banking percentages are cumulative. For example, if you have 200 points, and bank 75 of them in February, you could only bank 25 more (50% of your total) if you call to bank between 4/1 and 6/30. If you call to bank more, but wait until 7/1 or later, you could not bank any additional points because you already have more than 25% of your annual total banked for that use year.
If you just bought, don't worry if you aren't in the system yet. (If you already have a member number, you can call MS today or tomorrow and bank - no worries).
If you don't have a member number yet, just call MS (or your guide) when you get one and MS will bank your points for you. This is a common occurence for brand new members, so don't worry about it. This assumes you bought directly from Disney.
Best wishes -