Socketing Vanya for whm

So i did a search but didn't find anything, or found conflicting information.

Just need a little advice before i start socketing a vanya chest as i'm pretty sure if i mess up and have to remove materia I lose it all.

Also, picking up a piece of myth gear and wondering if its better to get boots and make a vanya helm or get the helm and darklight boots. Obviously if its not a big difference not buying potash is easier.

For vanya it can take 8 spell speed and piety or crit check xivdb.com for more info

That site wasn't actually pulling anything up for me once i selected the vanya chestpiece. >.<