you first call would be on the 8th - ask MS what the period you are looking for looks like.
if MS tells you busy call each day - then DO IT.
if they say plenty not a problem - then you can wait until the last day to make your entire reservations.
If it is a busy time and you need to make by reservation day by day - tell the first CM you talk too how many dates you are planning on getting.
then when the reservation is completely filled within 10 days after you will get your reservation confirmation.
there is no reason for MS to link on reservation. This is taken a big chance on your part. Days can easily be added to an exisiting reservation.
if you are linking your reservation - you have a different reservation number - at the
DVC resort you can be forced to leave and check back in each time the reservation number changes. Not in my opinion a good plan.
the ones times I have noticed a problem are Thanksgiving, the first weeks of Dec. For BCV and BWV the wine and food festavial in Oct/Nov.
spring break varies alot. Some weeks are busy, other times you can call a few days before you leave. Same with most of the summer. Most DVC don't like to go to Orlando when it is as hot as it gets in the summer. Parents with school age children generally can only on in the summer or spring break - however many have discovered Thanksgiving.
Thanksgiving is a great time to go. The weather generally is very nice. One big problem each and every year Thanksgiving week at WDW has become more and more crowded. It is still better by far than Easter or Christmas to NY. but each year it is getting more crowded.
Thanksgiving week also is one of the few holidays that you can get away with most of the week on less points. (Labor day is the only other US holiday that works this way).
So if you are flexibility say you want the first week of June it is not availability but the last week of June is and you agreed to take that one. You can definitely stay in all the DVC resorts with little or no problems.