I'm still looking for the prevailing view on if owning the one unit I can call at 13 months or 12.
I would personally start in the studio while I have lots of energy and enthusiasm for exploring whatever area I'm in, and then settle into the 1-BR for some relaxation before returning home. I pretty much hate studios though, so want to get it over with!
If you own one unit, you can reserve at the 12 month point. It is my understanding that you can split and reserve the first "half" at the 12 month point and the other half for the same or following week. But this needs to be done via phone. The on-line reservation system only handles the 12 month reservation.
If you own two units, you can reserve at the 13 month point. You can reserve both for the same week or consecutive weeks. So, if you are reserving consecutive weeks, you'll reserve the first one at 13 months and the second at 13 months plus 1 week. Or if you own 3 weeks, the last res could be as far out and 13 months plus 2 weeks.
BTW, Marriott opens reservations for an entire week at a time. The week starts on Thursdays for DSVs. So, when you call in at the 365 day point for the week that starts on Thursday, you can reserve Thur, Fri, Sat, Sun and Monday (all are check in days). Once you are in the system you can look through the Marriott library documents for info like this. I suspect that some owners don't know this and call in, for example, a Sunday check in at 365 days before that Sunday check in. In actuality, that check in day was available three days earlier. Shhhh... don't let the secret get out.
With my white weeks, I split them and reserve all for Thanksgiving (for the highest TDI), then I exchange them. I always try to take the efficiencies and with the help of the ii upcharge and ePlus, I end up exchanging into a 1 or 2 BR - - often at DSV1, 2 or Shadow Ridge, Newport Coast, Timberlodge, etc.