Of course the best time for seeds to germinate is in Spring as then they have the whole summer to grow on. If you live in colder zones, it can help to pile some leaves and larger twigs around seedlings to give them a little winter protection. If the seedlings do not get both of these requirements they will exhibit spindly growth and will have a difficult time when eventually transplanted to the garden. Don't over do it. You need only fertilize when the soil has warmed up and things are in full swing-this is in fact the only time they can use the fertilizer.
Seed germination is more of an art than a science.
You will find some batches of seeds sprouting before you expected and some later than expected. Perhaps the single most important point in cold stratification is sanitary conditions. Be patient when cold stratifying seeds-give them the recommended time and a few days or weeks extra for good measure. Don't over water, over dampen anything. Fertilize your seedlings only when the weather warms up-this is the only time they can actually use it anyway.