You can complete the General's tasks at any time you choose, but it is HIGHLY recommended that you follow the instructions in the order that they're given. Otherwise, you risk slowing down your Sector's development by using up your resources too quickly. You'll also be passing up an easy opportunity to earn Crystals early in the game. Some of the rules and instructions are complex, so take the time to learn how to complete basic tasks. If you wish to skip ahead, you can refer to the Guidelines menu.