SSD's and HDD's

[Hawick]

I have an SSD and an HDD. I'm building the computer from scratch.
Should I only install the HDD after I put an OS onto the SSD? Or should I just put them both into the case at the same time?

I've heard the first way is easier as it saves confusion. I'd like someone else's opinion

 

[Samat]

It's usually best to only have the drive you going to install the os to plugged in.

 

[USAFRet]

Have only the target drive connected. You can have them both mounted in the case, just leave the cables off the HDD.