With the exception of New Years and MLK weekend, January isn't typically overly crowded. You should be okay to find something six months out.
For your second trip, you have several options. The easiest is to borrow your own points from the next use year. You can do this as part of the booking process, either online or when booking by phone with member services. If you're still shy a few points even after your maximum banking/borrowing, another option is Disney's one-time-use points. You can purchase up to 24 extra points at $15 per point directly from
DVC when booking. You need to do this on the phone, as there are no provisions to do it when booking online. You are permitted one transaction of one-time-use points per use year.
If that still doesn't get you there, you can use the rent/trade board here on DISboards or a points rental agent like dvcrentals.com to put you in touch with a member who is looking to rent some of their points. This is a private transaction between you and that other party, and Disney will not get involved if there's a dispute. For this reason, you need to be cautious of fraud. Read the stickies on the rent/trade board, and be an aware buyer.
Caveat emptor!
As a member, you'll have two types of rental to consider. You can either find a renter who's willing to transfer the points from their account directly into yours, or have another member book some of the nights of your vacation using their points.
With a transfer transaction, you are the one who books the reservation and controls everything. You can mix & match your points and theirs on the reservation. (If booking at the 11-month point, you'd need to find someone with BLT points to rent.) The down side to transfers is that DVC only allows you one per year (either a transfer in, or a transfer out. Not both.) For this reason, someone with a lot of points they're looking to rent will want to find a member who wants them all. You may find it difficult to find someone who only needs to get rid of 20-30 points.
The other type of rental, the one that's more typical, is to have the other member book some of the nights for your trip using their points. That member retains control of the booking, and member services will only speak with them regarding that booking. You can still do an online check-in, but any other pre-arrival transaction would need to be coordinated through the other owner. You can link the reservation made with your points with the reservation made by the other member. This will allow you to stay in the same room for the entire stay. However, they are still separate reservations, and you'll need to physically do a check-out/check-in at the front desk on the cross-over day.
