Clean your filter based on the pressure drop increase not a certain amount of time. One of the biggest problems with cartridge filters is over-cleaning. They actually work better with a little debris on their surface. Most manufactures recommend cleaning when the pressure increases bu 8-10 psi from clean. I prefer to clean when the pressure increases by 20 %. There are so many variables that affect filter clean intervals you just can't do it by time interval. Things like dust levels, covered or not, pool use frequency, tree coverage, and filter size to name a few. I have a pool a little smaller than yours but it's covered with a screen enclosure and we have a 200 sq ft filter in it. I clean it 2 times per year using one of those filter comb attachments to my hose.
An easy way to keep tabs on your filter capacity is to get one of those gauges that you can reset the bezel to line up with new pressure. Then just watch the needle rise to the "clean filter" mark.
We always recommend cleaning a filter based upon the filter's pressure gauge... To do this you need to know what the pressure is when clean and then when the pressure increases by 25% it is time to clean the filter.
In your case with a CCP 320 filter, it should take months, not weeks, to get to the pressure that requires cleaning..
When I first took over my pool Kim helped me a LOT. One of the best tidbits of advice was to test on the schedule recommended and I'd "get to know my pool". That seemed a little weird to me but it's true. Every pool is a little different. I've tested it so many times I pretty much know how much bleach or acid to add. Plus the rest of the chemistry almost always turns out as I expect. There are never any surprises. If I'm going out of town for a while I can easily predict how much excess FC to add and when I get back the pool is perfect. With your SWG your pool life is going to be even better! (I'm in the process of adding that now)
Our 20 to 25% suggestion is made to cover all kinds of pools. filters and plumbing... When it gets to 25% and you clean your filters, if you find the filters are still pretty clean, you can adjust the percentage you use to match how your pool works... It is not a magic one size fits all number.. Do what makes the most sense for you and your pool.