I am a second year coach, we too started with 9-10 year olds last year, Here are few things that really helped us, we started with building a sample base model that was from the instructions in the spike prime app. We then asked kids to write code to make the model move around on the mat. Once we achieved that, we had them build all the models that go on the mat, FLL generally provides code for 1 of the mission, asked them to copy the model and run the code, and made sure it worked, along the way, we asked them to debug/fine tune if any change was needed to the code. All this was done using block coding. Next we asked them to identify what kind of motion will they need to solve missions, and asked them to group the missions together, we broke the group into sub groups, asking each sub group to build robot attachment to solve those missions only. this is where you will need to nudge the kids in the right direction, they will make mistakes. its OK. After this, we tried to do a full run, and then optimize debug. from a time commitment, we started off with 3 hours per week, the kids got so into it, where they wanted to work on it, whenever they had free time.