This formula's own materials are direct about this specific flexibility: morning before breakfast or evening after a meal both work.
Rather than mandating one fixed time, this formula's own materials name two specific options and emphasize that staying consistent with whichever one you choose matters more than the exact clock time.
Choose whichever option fits more naturally into your existing daily routine, since this formula's own materials frame consistency, not the specific time of day, as the more important factor.