Help! I entered the wrong date of a trust payment.

You can reverse it, but note that the reversal transaction occurrence will forever be recorded in SB.  The correction will nonetheless be made and reconciliation will be fine. 

For appearance purposes, it’s not so good if you share your IOLA transaction history with the client on invoices, as the reversal will appear on the list.  Not the end of the world, but it may lead to a client follow-up question or two.