Daisy, I share your sense of foreboding, or maybe just uncomfortable uncertainty, when it comes time to start a new batch of seeds. There's a whole ritual going along with it where I cook the soil and get the moisture just right during the setup. Maybe I should include some chanting or swaying to get my plants in the right groove.
My experience with germination has been quite variable with respect to time and viability. Right now I have about 8 pots set up with seeds over the last couple months where nothing at all has happened. But then something will pop up when you least expect it, so I am leaving them alone in good light. Some seeds are just plain more reliable that way than others, at least among the ones I have sowed. Fresher is better. The best way to get a sense of how this works is to just try. Ideally over the course of 40 years your odds go up significantly.
To add to the previous comments about growing succulents from seed, a couple of observations. You can find cactus seed in the grocery store: prickly pears (also called tunas) and dragonfruit. If you want a very specific kind of seed, try Mesa Garden, quality assured. Or if you go for the cheap trial pack of mixed plants, be aware that different sizes of seed behave in a qualitatively different way. The big ones (like many aloes and agaves, or the prickly pear) tend to sprout fast and get off to a quick start, due to the stored up energy. The sooner they become independent, the easier it is for you. The small seeds require a lot more babying, or maybe just being left alone with the right level of humidity. Plan on leaving them under clear plastic or a dome for months unless you like misting (which strikes me as more work but maybe that's a good ritual if you like it).
