Change A record to a C record without interruption

Hello,

I have a very small question.

Our DNS is managed by OVH.

I have a A record, which I'd like to transform into a C record

As I cannot have an A record and a C record at the same time for the same name I have to do following:

1.) delete the A record
2.) change the C record

I wanted to know whether there is any risk, that my server is not available during the transition.

If yes, what would be the correct way to do this without any perturbation