For our recent vacay, we booked in March for a July check-in. I don't want to wait that long for next year's dates. We weren't picky about dates last time but will be this time (we'll want to be at the World for 9/16 and 9/21). Is there a time of year that is most financially beneficial to book? We won't be on a package... I don't think. Probably room only...
Not sure I understand your question... I think you are stating that you have a specific time you are going to go there and are wondering if a specific time of booking it will give the lowest price, right?
If that is the question... then there is no set rule for the Disney resorts... you have to start watching them for special prices at least 6 months prior to the date you plan on being there... you need to keep abreast of specials for annual passholders, when they show up they can sometimes be a deal worth getting even though someone has to buy and annual pass to get the discount (remember only the person getting the room needs the annual pass, so if you are going to be paying for the room then only you need it not your spouse or kids they can just get regular tickets to the park).
Also sign up for any Disney internet site you can think of and provide your address and email, that way you increase the chances of getting special offers which can vary and seem to be a bit random in who gets what deal.
Also check your
AAA and see what deals are available from them, sometimes they offer better deals than Disney (not often but possible).
Now, for your plane tickets start signing up for all the airlines programs now so you will get emails when they have a special deal. Depending on the city you live in some airlines might have special airfare to Orlando from time to time.
Lastly your rental car... this is the easiest one to work with because you can make as many reservations as you want and it doesn't cost anything to make them... start by going out there now and making a reservation at the best price you can find now.... Then at least once a week go and see if you can find any better deals and if you do make a reservation and cancel the old one. Rental car rates are very volatile and can vary drastically for the same time period and same car... also consider renting a car from a site that is not at the airport this will avoid you paying the special airport concession fee, and in most cases you can set it up where you drop the car off at the airport on the way back for no additional fee (yes it might cost you $15-20 for a taxi but you can save much more than that in avoiding the concession fees)...