I noticed - while demoing SDS - that many player "declare" what they want to do before rolling dice for activation ("this soldier tries to reload his musket!").
Note that this is NOT required by the rules and should be avoided. Just declare which model you are going to activate, roll 1, 2 or 3 dice and then decide what you want to do. The same applies to Group Actions: each model in the group gets the number of actions you generated and then each model can perform that number of actions. What each model does is up to you :)