How early should you start seeds for outside planting in your garden?

I mean your tomatoes watermelon, peppers, to be sure that they will grow successfully when you transplant them into your garden.I live in Central part of Michigan.

How early should you start seeds for outside planting in your garden?
Probably about 6 or 7 weeks should be long enough.
Reply:There is a planting guide for your part of Michigan. Try to look it up or ask a nursery in your area.

I know SE Michigan and NE Ohio we normally plant around Mother's day when the danger of frost is gone. It would seem that in Central Michigan that about the 3 week in May would be appropriate.