Hi Shaun,
Yes, there is a difference in the time that it takes for the different additives to fully achieve equilibrium in a tank. Additives such as calcium chloride and magnesium sulphate will fully mix and equalize quite rapidly, and depending on factors such as water circulation volume and amount added, one can test within an hour or two. Additives such as sodium carbonate and sodium bicarbonate, and commercial additives such as Tropic Marin's Bio Calcium, all need to react with the CO2 in the water before they can fully reach equilibrium (the ratio of carbonate to bicarbonate depends on the pH of the water, which in turn depends to some extent on the amount of CO2 dissolved in the water as carbonic acid). For this reason, I prefer to wait at least 12 hours before I test for alkalinity / hardness.
Kalk (if dripped properly into a high-flow area) is an ongoing process, running 24/7, and for this reason I believe that one cannot really test it's effect specifically. One can (and should) test at least every week or two to confirm if it is maintaining the calcium and alkalinity - at least until one has determined that it remains constant.
Hennie