The Dampsticks usually appear slow to start in winter months as there is less airborne moisture, but in fact they were working straight away.
Once the temperature in your containers warm to above 5 degrees they will work even faster. It’s at this point that airborne moisture materialises and the warmer the air in the container, the more moisture.
If your used two are now full during the colder spell, then, yes, definitely exchange the full with the two spares and keep an eye on them, as you may find there is a lot more moisture still held in your stored items, yet to be revealed and that will happen a lot quicker in the forthcoming warm months than the previous cold.
People incorrectly think damp and condensation only occurs in the winter, in confined spaces, such as shipping containers in which it’s actually much more prevalent. The biggest market for de-humidification is in the hot countries as warm air draws and holds more moisture.