I think that as with any food you should be able to apply common sense along with smell, look and feel. If it starts to smell a bit sweet and weird or goes sticky or slimy or looks unappetising its done. Since it's your first batch just keep enough in the fridge to last 1 week and freeze the rest, then depending on how well it keeps you will have a guide for the future. The least time it should last is about 4 days I would think, after that the salt and cure should give it a few days more, after that who knows