Most newer fish hobbyists seem to test right before water changes, and maybe a spot check here and there. Experienced hobbyists vary - some don't test at all, some test occaisionally when there seems to be a problem, and some test weekly.
I test my waters after my water change and before I add any conditioners (Nova Aqua + Amquel + and Immune Plus) I know where my readings are from week to week as my tanks are well established. I have set days I do water changes and I don't stray from it often and I'm not over stocked. Be careful not to over feed!
I do water changes every 5 days in my 265g and my Goldfish tank and every 10 days in my Betta Tank.
When you become more familiar with your tank and fish and your tank becomes more established then you will be able to relax a bit more and test less often. Until you get to this point I suggest a little more frequent testing.
Some govern their water changes by their readings and I can see their point to some degree. However, there is no excuse not to give your fish fresh water and on a frequent basis regardless of perfect readings. Fish have to have fresh water to survive.
I've been doing my water changes on Saturdays and testing b/4 hand. I've been thinking of testing every other week, because my nitrates stay so low, 5-10. And yes, its great to be done with the cycle!!:;bb