Basically the short answer to this is, “The sooner, the better.” This is especially true for those who have never put together a Halloween haunted house. These are really a lot of work, and it will take months of planning, and Halloween prop making in order to pull it off.
If you have done a haunted house before, then you’ll already have some props, and Halloween supplies, as well as some idea of what you will be doing. For the sake of simplicity, we’ll assume that you have never put together a Halloween haunted house before.
The first thing you need to do is decide on what your haunted house will consist of. Will it simply be a yard haunt, or will it be more elaborate, with a temporary construction in your yard, or garage? The larger your haunt, the earlier you will have to start on it.
Most people, who have been doing home haunts for years, actually begin their planning phase as soon as winter is over, if not sooner. This is a good rule to follow because it will give you plenty of time to get your supplies; start building props, and laying out your floor plan.
Warm, mild weather is somewhat important because much of your prop construction will have to be done outdoors, unless you are fortunate enough to have a workshop, or garage. Even though your Halloween prop building will have to wait until warmer weather, you can start the planning phase at anytime, though you should plan to be finished, and ready to go by at least the first week in October.
The first year you put on your own Halloween haunted house, out of necessity it may be smaller, but don’t be too surprised if it grows each year, and one day you find you have this monstrosity of a haunted house, that takes you a month to put up. Storage can also be a problem; half our basement is filled with Halloween props.
To start planning, write down exactly what your theme will be; once you have this, you can decide what the layout of your haunt will be, and what props you will need to create the perfect home haunt.
Researching, or buying your Halloween props will take some time; so keep this in mind. A good rule of thumb is to work on one room at a time. For example, if you plan to have a crypt room, get all the props prepared for this room, and then move on to another.
I have always started my planning phase in about March, and began the actual construction of props in late April or early May, but of course much of this depends on what the climate is like where you live.