To come up with antonyms for the phrase "doing top of head," one could consider words and phrases that convey a sense of planning, intentionality, or forethought. Some possible antonyms might include "careful consideration," "meticulous planning," "thoughtful preparation," or "methodical execution." These terms all suggest a deliberate approach to decision-making and action, in contrast to the spontaneous, off-the-cuff nature of "doing top of head." Other antonyms might include words like "deliberate," "intentional," or "calculated," which all suggest a conscious effort to plan and act with purpose. Overall, antonyms for "doing top of head" tend to emphasize the importance of careful thought and intentional action.