What is the best time to take 81mg. aspirin or baby aspirin to avoid another tia?

Same time: Due to aspirin's effects on the platelets, as long as you take it at a similar time each day, the particular time of day does not have such a great impact. Control of other risk factors such as smoking cesstion and blood pressure control will also be expected to significantly impact the likelihood of future tia/stroke events.

Morning: Morning, around breakfast time is fine. You can take it with the rest of your morning medications if you have any.