There are zero good reasons not to reconcile with a brother… immediately.
Ephesians 4:3 – “being diligent to keep the unity of the Spirit in the bond of peace.”
Matthew 5:23-24 -“Therefore, if you are presenting your offering at the altar, and there you remember that your brother has something against you, leave your offering there before the altar and go; first be reconciled to your brother, and then come and present your offering.”