Credit Notes involving Exchange Variance

This may be a questions for accountants

With cases dealing with exchange variance, or in our case gain/loss.

1) Let's say we created a Credit Note for x Date for a Foreign Account.
2) We then let's say 5 months later decide to allocate that Credit Note to a overdue invoice.
3) When we apply the allocation, it automatically creates an exchange variance posted on to the day the Credit Note was created.

If a Credit Note was not yet allocated to any invoice before Year End , would the exchange variance post in this case screw up year end? Should the exchange variance date posted be a different date, like perhaps the present date ?

Thanks