Whether walking can work at 7 months depends on circumstances. If you are trying to walk to a high demand time, it has little chance of working because resort owners will have you blocked, e.g., finding openings at 7 months out in the third week of Nov is not going to allow you to walk into Thanksgiving time. However, things like a one day walk may work despite the resort owner reservation risk, e.g., for a Saturday start date in mid-July, one of DVC's lowest demand times at WDW, you see a BWV standard view studio open for eight nights, Sat to the next Sunday, and what you actually want is the Sunday to the next Sunday. You reserve the Sat to Sat, leaving the need to walk only one night and you would call the next day and make the change. Chances are likely good an owner won't fill that one night that you need but you would have a high risk someone else would grab that room seconds before you could at exactly 7 months out for your Sun start date.
