The best time to get on a Pool Service Company's schedule for a swimming pool closing is right around September for the earliest and least expensive closing price.  Generally, the company will send out pre-printed closing flyers that allow customers to choose the range of dates that works best for them.

Close your pool early if you are not going to use it in the Fall.  If you decide to use the pool and keep it opened, then it is crucial to keep it properly maintained with chemicals.

Hint: It is real common for a pool owner's intention to use the pool at the end of the season to fall apart.  Then when the pool does not get used, the pool also does not get maintained as well as it should.  As a result, the pool turns green.  Then it is common for the owner to try and maintain it all at once, by over chemicalizing and scrubbing abrasively just to put the cover on.  This mentality works against you and creates all kinds of problems.

Remember: Close your pool early.  If you do wait until the latest mooment to close, maintain it very well.  Lastly if you do not do a good job keeping it clean and clear, then do not over chem and scrub.