Yep, that's what I was talking about. I usually let mine mix for 24 hours or more (usually a week).
A good tool to get would be the Milwaukee pH controller. For about $100 you could use it to check your pH easily and later if you got a Calcium Reactor you could then upgrade to an Aqua Controller and use the Milwaukee in the CA reactor to control the CO2.
Or get an Aqua Controller now and it will keep a log of your pH, but it's a bit pricey, and you could rule out the pH or figure out the swings are too great.
I don't like testing pH with kits because they are difficult to read accurately.