I wouldn't bother spending the money to get the test strips. I made the mistake initially of buying test strips, and once I found out they were not very good at accurately testing low levels, I bought the liquid tests.
It just so happened that when I cycled my second tank and couldn't understand why a PWC wasn't making a difference in the reading from the liquid test, I decided to test with the left-over strips that I had. With the strips I was able to detect that my levels were extreamly high and made sense why a 50% PWC wasn't making a difference on the levels seen in the liquid tests.
In any case, if you are trying to cycle the nitrites and you don't see your levels changing after a PWC, then do a couple of MAJOR (50-75%) PWC, testing after each one, until you start getting some valid readings.
Worst case, you do the equivilant of a 100% water change and all your levels go to zero. No big deal. Your still adding ammonia to the tank daily, and within 24 hours, your nitrite levels should be moving back up. If ammonia and nitrite both remain at zero, check nitrates. If nitrates are rising and ammonia and nitrite stay zero, you will then know your tank is cycled. But if it is not cycled, like I said, your nitrite levels will quickly go back up when you continue feeding ammonia to the 1st bacteria.