Well things that are hardy in your area go out now like hardy annuals, reseeders and perennials. There are a few plants that like a cold start or need stratification and those are perfect for now.
Half hardy and tender annuals get planted after your last frost date usually.
I really suggest you check out the FAQ's they are full of good advice and pictures. :)

Just wanted to say welcome heartzlink!

I found the information on wintersow.org a great place to get a feel for what to start when. Here is the link for zone 7. Hope it is helpful.

http://wintersown.org/wseo1/WS_Database_Z7.html

Welcome Heartzlink,
I've been gardening ...Hmmm, never mind,... a long time, ok?
And I still don't know botanical names. The plants grow just fine with out the pedigree.lol
I'm in a different zone than you so I'm no help, But Token will come along soon.
:)Laura

For starters, perennials (hardy in your zone) can be sown any time. Most plants are marked as annual or perennial and zones given. If you don't have a commercial seed packet that shows that information, try a google search on whatever name you have for it.

It's a little trickier finding out whether something is a hardy annual, a half-hardy annual or a tender annual. If the packet indicates you can plant directly or transplant outside before the last frost date, that will give an indication of hardiness. The FAQs here and the wintersown.org web site are both helpful. Also try searching on the plant name (common or latin) in the forums here. Another site I've found very helpful is selectseeds.com, which tells which category their plants fall into.

For veggies, you can check out your state's extension offices or university web sites for info on warm and cool-season veggies. In zone 7 Virginia, you will have similar climate to east Tennessee, where I am. The UT site has a bunch of publications on home gardening - including which veggies are warm-season or cool-season here. Most are free to download.

Here is a link that might be useful: UT home gardening publications

I think most of your questions about what to sow when have been answered, so I'm gonna tell you how we got so smart. For me, it was lots of late nights in the fall of 2008 reading as many threads on here as I could. I also used google a lot to find out if the species plant was native or if the seeds I had were hybrids. If it was native, I'd sow it early. If they were hybrids or I was unsure, I'd sow in the late winter, early spring. I had some failures. I sowed amaranthus too early and lost the whole container during a snowstorm. I also lost my annual alyssum, but the perennial survived. In between trial and error, I asked questions here too about specific plants.

These days, I'm a lot less worried. I save some seeds in case I sowed something too early. Once I start planting out, I give the seeds away or trade them for annuals that I can sow later. I've already got sprouts as do many others in zone 7. The green tide starts here early. So put out your hardy perennials and reseeding annuals whenever you want. Only a few seeds need cold treatment, and even then, some will still sprout without it.

So dive in. Ask and read everything you can. Chances are, if someone hasn't grown it before, there's a resource online that will help you with your searches.

And welcome!