I put it on the stage to protect my jump to ledge while also protecting the Din. If he got ledge or up b'd to the stage I would still have the Din and a punish. If you put the Din below the ledge you almost always have to detonate it as they recover or they will knock it away.
It really depends on the type of recovery I'm edge guarding. This is very early in the match so I haven't found out if Vivith sweet spots every recovery, and Mario's up b can power through Din's very easily.