Mervyn, there are reports of people having faster cycles if they do a water change to get the nitrite reading down to somewhere on the scale. It appears that high nitrite and nitrate can inhibit the nitrite eaters so they multiply slower. Dosing slightly less ammonia (to 2ppm) will result in less nitrite being made so it won't go up as fast. Once nitrite is being cleared, you then increase the ammonia dosing again. It's getting the bacteria started that's the slow bit, once you have enough to clear 2ppm ammonia it takes very little longer till they can clear up to 5ppm. Under optimum conditions these bacteria can double in 24 hours (though our tanks are rarely absolutely spot on perfect for them). The problem is that we start off with very few so it takes many doublings till we get anything like the number a fish tank needs.
Nitrate is the most difficult parameter to test in the home. My younger son used to work for a water testing company and he was highly amused at the thought of us trying to accurately measure nitrate with our testers - his company used very expensive equipment to do it.
You have obviously heard of the main problem with homes testers. One of the reagents in bottle 2 (or bottle three for 3 bottle kits) tends to drop out of solution, which is why the instructions say to shake it so much. And banging the bottle as you did breaks up any lumps that can occur if the bottle has stood a while.
I wouldn't worry too much about your nitrate level just yet. Next time you test, bang the bottle again, and shake it for longer than the instructions say - I've seen people advise to shake till your arm feels like it's falling off, but that is a little extreme
Or buy a Salifert tester. They do fewer tests per tester so that they work out more expensive but they are reckoned to be the Rolls Royce of test kits. They are powders rather than liquids which gets around the problem of reagents solidifying on the bottom of the bottle.