If you want to be a bad product manager, start developing a product and release it as soon as possible. If you’ve got a good idea for a product, why wait? You need to get it defined, get it developed as quickly as you can, and then release it right away, without any delay. Everyone knows that the first product to market usually wins, and the sooner it’s released, the quicker you’ll be profitable.
If you want to be a good product manager, consider your market window as part of your product strategy.