inside Seed Sowing For Fall

I have a couple of questions that i hope does not confuse everyone in a 3 mile radius. I live in Zone 8 in Florida have went to different calendars on seed sowing for fall. Well 1 said for June 30-Aug 14 to sow seeds indoors on some things. So Saturday I started Broccoli, Cauliflower, Brussel Sprouts and a few tomato varieties. Well come Monday most of everything has already germinated and sprouted up in my seeds starting trays. (was NOT expecting that to say the least) Well now I am wondering if I did not start them too early. Do I take the top off since some germinated? What about the ones that did not? Shouldn't the cool weather stuff go out later in the year? How long should you keep seedlings in those trays? How long should seedlings be left in those pods before you put them out anyway? I am wondering why the calendars show so many varying dates from one site to the next. I am a newbie at all of this and I think I may have jumped the gun not knowing. Then I wondered should I have followed the schedule from where I bought the seeds, i am just not sure of any of it now. I have googled everywhere to answer these questions but everything is so cut and dry about things and not specific. If anyone has any advise for a newcomer to gardening please help me! This is all so confusing to me when I guess maybe it is not to people who have been doing it.

Thanks

i think that there is a lot of variation because perhaps each one is being influenced by that specific authors own experiences, also you have to watch to make sure that the guide you are talking about is for your own specific zone. Me being in zone 7A for example, i will be able to start some things come late august. The lingering summer heat will give them the boost they need to get going well, and by the time they mature it will be cool enough that they will remain in great quality.

One sure fire way i have always heard is to find your average first frost date, and then count the days backwards however many days it says your crop takes to mature, plus add a couple of weeks for germination.

jmc is right.
Look up some very local climate data (for your city, not all of USDA zone 8) and see when the average frost date is.
Most of the crops that grow in cooler weather ripen in about 2-3 months, though some (Brussels Sprouts, IME) take longer.
As long as the days are getting shorter it is OK to start most of them before fall, and they will be OK. Growing leaves and such for a bit while it is still warm, but ripening the crop as the weather cools off.
These crops sprout in just a few days, and are ready to plant out in a week or two, depending on what size container they are in.
You could transplant them into about a 4" pot to keep them growing, if the garden is not ready yet.

So go ahead and plant these out when they are ready (and there is space in the garden), but I would start another batch of seeds (not tomato) in about a month.

Monitor which group does better, and which varieties do better. Then you can mark on your calendar when to start the seeds.

Tomato is a warm season crop. In the northern hemisphere most people start the seeds in the late winter to spring and plant them out when the weather is warm (just after the last frost date in their garden).

You can also stretch the seasons by covering the plants with clear plastic in the late winter/early spring to keep them warm, and warm the beds, or the same into the cool months, and get a harvest as much as a month after the frost starts.