Season started on March, 5, with barely 10 hours of daylight. I planted seeds of salads (mâche, deer tongue, arugula), of Swiss chard (Virgo), peas (Karina), spinach (Monstrueux de Virolay), and parsley (Giant of Italy). These are all frost-tolerant plants that I can take into the garden somewhere in April.
Deciding on what date to start the new planting season depends on several variables: your local frost dates, hours of sun light in your latitude, the time your vegetables need to mature, and how cold or frost tolerant they are. If you are using grow lamps and heat mats you can play with these variables. I will post later some thoughts and tools about how to figure out what to plant when and in what order.