Up to you about when to book. Others will say if you book the room, it lessens the chance of an offer coming out. If rooms are booked there is no reason to give a discount. I on the other hand take the chance and book hoping for a discount. I’ve been burned in the past waiting until a discount came out only for the rooms to be full and I would’ve stayed there regardless of a discount. I booked for poly next October and crossing my fingers that rooms won’t fill up. Next year will be tricky. It will be when galaxys edge opens most definitely after you plan on going. So either it will be busy because people want to miss the crowds or it might be dead in October because they are waiting to visit Disney once GE opens. We won’t know until it gets closer and maybe a definite open date is announced.
Which resort were you thinking? Some resorts almost always have a discount and you will find October to have good discounts but some blackout dates. You can look back at past discounts per month on mousesavers.com.