Timeline
Round 0: Form your strategy
A beginning is a time for taking the most delicate care that the balances are correct.
Before the game starts, take as much time as possible to analyze your situation, and the situation of the other teams. When you think you have a good understanding of the initial game state, try to define your company's goal. You should come up with something easy like "become the leader in the luxury segment of market 1". (Remember to make it SMART: Specific, Measurable, Attainable, Relevant, Trackable). Having a goal helps you allocate your resources more efficiently and keep track of your progress. The game will quickly become very complex and your vision of the market will become blurred should you chose criteria that are difficult to handle, like for example the accumulated wealth of the different teams or the price of the stock.
Whatever strategy you choose, do not stop revising it until you are completely sure that it's going to work. On that basis take your first decisions.
Round 1 - 2: Checkup
In this period you should verify if everything went as planned. Can you stick to your strategy? This is your last chance to change it. Changing your global strategy during later stages of the game can be very dramatic. Therefore rethink your strategy. And then begin to sketch out a Marketing Plan and think about team organization.
Round 3 - till end
Your company's running. You have a plan. Stick to it. However do your corrections, adapt your Marketing Mix and apply tactics.