Entrance door lacquer and stain

I have just ordered a new front door.

It is a sliced Pacific Maple veneer with a honeycomb hi density core.

I am going to probably clear finish the door.

Should I do this before it is hung?

I am getting someone who knows what they are doing to hang it.

I will lacquer it.

It says on the site where I got the door from to seal it before hanging then lacquer/paint etc.

What do I seal it with?

Thanks.