If it were me, I'd do it now and have some sort of "deadline" in mind. When the deadline arrived, I'd cancel the exchange request if it hadn't come through and use the points for something else. Can't hurt and might work. Good luck!
For the most part you can put any top resort during peak time on that list. Not to say it'll never happen, but not enough to make it something to count on or worth holding up other vacation plans for. You can likely pick the top 70-100 resorts on the DVC II list and figure out what the peak time is (a subset of red time as all red time is not peak time). For MX, Caribbean and south FL it's weeks 51 to 16 (Xmas to Easter). Jan is a little easier and for late in that range it depends somewhat on when Easter occurs. Some areas and resorts will have secondary peak seasons as well, for example, mid summer is a secondary peak for my example above but it actually varies by area a lot for the secondary peaks. And some resorts have such a reputation, are in such demand, and have such low number of deposits that you may never get them. Ocho Cascadas in PV, and the two you mentioned above come to mind. I'm sure there are others.
You are under a year out you have decreased your chances a fair amount. In this case it depends on where you'll accept. If you include the entire Caribbean and ? MX, you may get something, like St Marteen/Martin or a secondary resort/area of MX. It never hurts to try, just know what you want and when to cut it off. I would make a backup plan though as well as look for direct exchanges. If you could do a 1 BR you'll have a much better plan. I might be able to suggest some direct exchange options as well if you email me directly.
As a rule I agree. It's either not available or it's not a good value with little overlap. But IF one can get certain high value/high demand items, it can be a very good value.
