Walking before and after meals are both useful. The better choice depends on whether you want a dependable exercise slot, a gentler post-meal routine, or help fitting movement around fasting.
Walking before a meal
A pre-meal walk works well when waiting until later usually leads to cancellation. Some people also find walking comfortable near the end of a fasting window. Keep longer or faster sessions realistic, especially if you are new to exercise while fasting.
Walking after a meal
After-meal walks are easy to attach to an existing cue: finish eating, clear the table, then walk for 10 to 20 minutes. A relaxed pace is usually more comfortable than turning the session into a hard workout. Large meals may require a little more time before setting out.
A practical decision
If the main goal is accumulating steps, either option counts. Use the slot you complete most often, then add a short post-dinner walk when convenient. Estimate the activity with the Walking Calories Calculator, but treat the result as an estimate rather than permission to compensate with food.
Pair the routine with balanced meals, the beginner plan, and the practical guidance in Start Here.