It sounds like each board is just 2 circuits - lights, sockets - with 1 or 2 lights and 2 sockets total. If so, and everything complies and tests good, could probably manage all 4 in a full day, per James's post. This assumes my choice of board, and not something cheap and nasty that I'm not familiar with. But could easily take a lot longer, and I'd not give any firm costs without having seen them.