If there is anything I have learned doing this, it is to wait and meet the families before having a "decision" made in your head. I have had a lot of success with having older kids start with me (3 yrs +). In fact I will only take kids now part time if they are older.
See which kid/family you jive with most. Alternatively, if you like the full timer that won't start till Jan you could tell them you are not ready to make a decision right now and continue to advertise. If you can't find another full time family by the end of the month or mid Nov you could offer the Jan family the spot. A bit of risk with this though however most daycare's don't know if they will have a spot this early for Jan anyways.