This is just based on what we did this season. It worked out okay for us.
Week 1: Discuss the game, read the rules, draw out design ideas, write down the main things you want the robot to be able to do
Week 2: Vote on a final design and declare a winner, begin figuring out how to make it work
Week 3: Split into sub-groups that each work on a different aspect of the bot, Start building any prototypes you may need to test a part of your design
Week 4: Begin putting the pieces made by each sub-group together, figure out exactly how your robot is going to run (decide on which/how many motors you will use), make a power budget for all your motors if you haven't already done so
Week 5: Construction of the robot/attachment of all major parts (lots of machining, welding, deburring, filing, etc)
Week 6: Work on details that you haven't had a chance to focus on yet, run a test of your bot if possible, go through a check list of what you planned to accomplish and make sure your robot meets all safety and weight requirements, WORK LIKE CRAZY