I coated plates in April and exposed the last three just last week. They came out fine -- as good as the ones I made in April. The developer was fine too, but I was careful to squeeze the air out of the bottle before sealing and storing it. I know it's only four months, but it takes some of the pressure off. I can't speak to latent image stability. I would think you'd have a few weeks, but I would test it and wouldn't wait any longer than absolutely necessary. Coating may be a bit tricky, but they're relatively quick and easy to develop.