Hi when i found my snail eggs they were all hard and dry, and after about 2 weeks they went quite jelly ish and then the snails hatched.
One of my snails also died a few days after i found the eggs, but the other one is still ok.
You could still get some eggs if the snail you have left is female, as they can store the sperm for quite a while (i think thats right)
Hope that has helped :0)
1 Pleco, 1 Mountain Minow,6 Cardinal Tetras, 3 Rosey Tetras,3 Black widow Tetras, 5 Guppys, 1 Rainbow shark, 2 African dwarf frogs, 1 Apple snail and quite a few baby apple snails and some trumpet snails