I'd put the AMD in after you download AMD Driver software.
Then switch off power, disconnect power cable, press ON button on PC to discharge the PSU
Install GPU
Turn computer back on
Run DDU - do exactly as it says
Then install AMD drivers
I'd always done it a little differently than @ElectrO_90 stated, but can't say for sure if his steps might be better/easier or not.
My process has always been (even if going from one AMD card to another, or one Nvidia card to another):
1 - Download the latest drivers (in your case, from AMD) for the new card, but do not install yet.
2 - Download and run DDU - choose the option for removing/replacing video card.
3 - The system should shut down after this, if I recall correctly. If not, then power down.
4 - Remove the old card and install the new one.
5 - Power the system on.
6 - Install the drivers you downloaded in step 1.