Hi Mark,
I have done this and found that it's best done together at the same time.I think that is an answer to your question.
The idea is to get the glass cloth[s] sitting on the wood surface and the second layer sitting on the first layer of glass,rather than have a skin of epoxy separating the two cloth sheets.The first cloth wet out is just enough to do just that, so making sure there is not enough epoxy thickness to let the cloth[s] float off the surface of the wood or the first glass layer.Less epoxy equals lighter boat.Glass locked on the wood surface equals a stronger structure.win, win.[Epoxy has low tensile strength,glass is massive]
cheers, from Paul.