It is important to say “no” earlier rather than later because we’ve learned that to wait until something reaches a higher value stage and then abort due to lack of capacity means losing more money and time. You can obviously say “no” either explicitly or implicitly, because by not delivering you end up saying what amounts to “no.” Remember too that your time is your one finite resource, and when you say “yes” to one thing you are inevitably saying “no” to another.
