The Scrum guide is explicit in this topic. “Scrum is founded on empirical process control theory, or empiricism” and “Three pillars uphold every implementation of empirical process control: transparency, inspection, and adaptation”. Considering that, the update of the Definition of Done is the adaptation of this, it must be performed ASAP.
Some doubts about the opportunity of the update of DoD, may exist, because the Scrum Guide says that “During each Sprint Retrospective, the Scrum Team plans ways to increase product quality by adapting the definition of Done as appropriate”, but after it says that “Although improvements may be implemented at any time, the Sprint Retrospective provides a formal opportunity to focus on inspection and adaptation”.
Then, the sprint retrospective is a formal opportunity for inspection and adaptation of the DoD, but this must be done when this is necessary.