Creditors have better memories than debtors; and creditors are a superstitious sect, great observers of set days and times.

Money owed weighs differently on the two people involved. The one who is owed keeps an exact ledger and counts the days until the date comes round, while the one who owes drifts, because the debt is only one item in a crowded life. That gap is where reputations quietly get made and lost. Assume the other person remembers the date better than you do.

Look at what you currently owe, in money or in promised work, and put the dates somewhere you will see them. Pay or deliver a day early where you can. If something will be late, say so before the date arrives rather than after.