Spring planting is about to begin here in Wisconsin, granted that the weather has been oddly unusually for this type of year. Neither the less it is not to early to your seedlings inside so that they have a head start when they are ready to be transplanted outdoors when the weather does finally decide to turn. In my experience an indoor greenhouse with a heated base that warms the soil and creates humidity inside vastly helps the seeds and seedlings get a  jump over the competition. There are many ways to do this, from the cheap plastic bottle cut in half with soil and seeds then the top placed back on under a heat lamp or my personal choice a seedling tray inside of an indoor greenhouse that has vents to let in/out air on top of a heat mat. The greenhouse and heat mat can speed up germination times by up to 50% though normally it only shaves off a fraction of of the time, in example a 10-15 day germination would sprout in as little as 7 days typically. So wither you are growing fruits or vegetables a head start on your planting will help you yield produce before others, staggering sowing times helps insure that you have plenty to harvest throughout the growing season and proper time for preserving the ones that you would like to keep for future use without the needed rush.