Longboard concaves/double concaves

Starting to shape a 9’ Performance Longboard…
Interested in adding nose concave (possibly to a double concave), then a V on the back third of board.

I am looking for general advice/information on how long should the concaves should be…

  • about where should I fade the nose single, into the double concave?
  • how far back from the nose should I start the nose concave?
  • about how thick should the deepest part (thinnest foil) of the concaves be?

I know there are multiple variables, but any advice would be helpful.
Board will be about 22.5 wide, 2.75 thick.

Thanks