Start building ahead of time! You should have ALL your workers building 24/7. The second a building is completed, move your worker to another building. DO NOT CLICK FINISH UNTIL THIS ALLIANCE DUEL DAY! If this is hard for you, like it is for me, there are 2 ways to help. Move all your buildings to the bottom of you fortress. Personally, this never worked for me. In settings there is an option to verify if you want to collect a build. If you have this option on, when you click a finished building, it asks if you are sure you want to recall that building. Mines are the quickest, but gyms and control centers are worth more points since they're longer and bigger buildings. Try to have enough buildings complete that you won’t need to use speed ups.