Question : Changing external DNS hosts -- am I missing anything?

I have been given the task of moving our external DNS hosting from AT&T to a different host.  I understand that I need to change the TTL on the current A records and MX records on the existing host.  After that, is there anything more that needs to be done other than entering the records on the new DNS host, enabling them, and then deleting the records off the old host?

It seems like a pretty simple process.  I just don't want to overlook something.

Thanks.

Answer : Changing external DNS hosts -- am I missing anything?

Actually, I would drop the TTL within the SOA record and change the default SOA to match (ideally an hour would be good) and do it one day + $currentTTL in advance.

Once the move is made, you can change both the SOA and default TTLs to something more reasonable.