The best time to be creative is while creating something.
Yes, it does sound contradictory. Yet it is while creating something that is when our mind is open and willing to generate new ideas during this process. Not everybody might agree. But I do believe that during the process of creation we discover new ways of making things or find flaws needed to be addressed. I have no doubt that the only way to fix something is by knowing there is something that needs to be fixed.
As makers we are always in search of answers, inspiration or other ways to improve our technique and therefore become more skillful. Taking time to understand the process, qualities and limitations of our tools as well as our medium shows us the route that we should follow to achieve our goals.
Giving ourselves the freedom to create for the sole purpose of exploring can be a valuable tool as we are not so concerned with the outcome, but more with the process.