If you are on the board of a charity then the end of December could create some drama. Canadian taxpayers want to get a tax deduction for the donations they have made during the year. You need to establish a policy about the dates on donation receipts. If you receive the money after 2017 then you should not give the donor a receipt dated in 2017 — as a general rule.
Some charities have a policy that if the envelope that the donation arrives in is post marked in 2017 then the donation receipt will be dated in 2017. If this is going to be your policy you need to decide that before the end of 2017, not after when you see how many people complain about the date on their receipt.