Now that you know your last expected frost date, count back from the last expected frost date for each type of seed you are planting and you'll have a planting schedule. If your plant is not listed here, check the back of your seed package for seed starting recommendations.
If you live in Zone 6 (Frost Free Date Range March 30 - April 30) and you want to plant broccoli, which should be started 5-7 weeks before the Frost Free Date, count back 7 weeks from March 30th to February 9th. That's the earliest you should consider starting your broccoli seeds. If it seems like it will be an early spring, go ahead and start planting then. However, you would probably be better off averaging the dates to April 15th and counting back from there. Holding the seedlings for a couple of weeks before transplanting won't be as stressful on them as holding them for an entire month.
Example From Prior Page
Recommended # of Weeks to Start Seeds, Prior to Frost Free Date
|Vegetable||# Weeks||Flowers||# weeks||Herbs||# Weeks|
|Brussels Sprouts||5-7||Batchelor Button||4-6||Chamomile||8-12|