When to upgrade oDS

Hi I was just wondering when the correct time is to update the ODS when doing a domino upgrade. I am upgrading from 7.0.1 and my plan was to upgrade the servers to 8.5.1 fix pack 2, then upgrade the clients. Once everything was running smooth( wait a week or 2) then I was going to upgrade the mail template and then the ODS. Is this wrong, can anyone see any problems from doing it this way. What way has other people upgraded the ODS?

Thanks

Subject: ODS

I did it as the very last step.