At 12-13 months only owners of a particular week at a particular can access the inventory and there should be no RCI fee to reserve. This is the only week that you can later deposit for points. Some resorts have you reserve directly with the resort others have you go through RCI. You should also not have to pay for a guest certificate if someone other than yourself will be checking in.
At 11-12 months only owners in points at a particular resort have access to the inventory. If you forgot to reserve your home week and it is still available you can reseverve it for $40. You can generally go down in season or size and save the remaining points for another time. For example I own a summer Hilton Head 3 bedroom unit. I can reserve a 2 bedroom unit at my resort at Easter and save the rest of the points for later. During this time frame you must reserve a full 7 days. The system will not let you use points from other resorts to make reservations during your home resort priority, you can only use your annual allotment from that resort. If you own more than one unit at that resort, they can be pooled. (I have heard that sometimes guides can override this and allow points from multiple resorts but I wouldn't count on that always working.)
At 10-11 months you can reserve your home group. Sometimes this is a developer group and sometimes a management group. If you own an independent resort you may not have any other resorts in your group. During this time the full exchange $ applies and you can reserve more than or less than 7 days. You are still competeing against less owners.
Its not until the 10 month mark that everyone in points has access to your resort and group. Most people in points let their weeks automatically deposit into points so this is the best time to look for resorts outside of your home group. Some develpers like DVC and Hilton deposit later, as do individuals who initially reserved and changed mind as well as cancelations so even if you don't see what your looking for at 10 months it might become available later. If you still forgot to reserve your week and want to use it you can do so if it is still available but you will be paying the full RCI exchange fee, can no longer rent it and would need a guest certificate if someone else is checking in.
Weeks searches for non points resorts can be done up to 2 years in advance but the search engine is IMO annoying and time consuming, but search in weeks with points is a different topic.