Best practice for welding 2 plates full pen. 1

[Java999]

Hello,

I would like to know what is the best practice for welding two 10mm thickness plates full pen as shown on the image.

Is it good idea to make a bottom plate say 10mm whider to avoid burning the edge?

What is the depth of melted metall of second plate?

 

[Java999]

KootK, thank you very much for your help!