I think you are fairly safe with those 3... all can take cold temperatures. You would probably be safe planting them out when the night temps are in the 50s.... maybe even mid-40s.

The middie of April is the best time to start seedlings for planting outdoors after June 1

Thanks! I think I'll transplant to containers in the next week or so and then I can just pull them in if - (and when in MO!) - the temps drop.

You might look for one of those plastic covered shelf units that look something like a bakers rack. A 40 or 60 watt light bulb on the bottom at night is enough to keep temps high enough to avoid freezing. I have found them for as little as $15.00 for 4 shelves. The light bulb and lamp is extra. Sandy
PS You are not the first or even the thousandth to start too early. LOL!

Once your seedings germinate and establish true leaves, (more than two or three), you can leave them outside.
Of course chives do not have leave. but when they are about 5" tall(even shorter) can survive and even grow at temperature of mid 30s to mid 50s (lows , highs). Same goes for parsley. But thyme and sage are very slow growing and need much warmer days to realy grow.

Just keep in mind that plants started indoors/kept indoors will need to be hardened to outdoor conditions and temperatures to improve the plant's chances for survival.

FataMorgana

Last year I started parsley indoors in early march. I ran out of room in the garden and did not plant the parsley until the end of June. By the time I planted the seedlings looked almost dead from neglect with only a couple of green leaves but they came right back and grew well.

Jon

Parsley and chives are very easy to grow.

You don't have to start them inside, just direct sow them
in the garden when temp are in 30s. They will know when to grow. Of course if someone wants then to grow early, then she/he can start them inside. I started my parsleys outside in cold frame and transplanted them in the garden when they had couple of true leaves. Now they can be used (outer leaves). With the chives I just dired sowed then in the garden and they are about ready to get their first cut, in oder to grow flat leaves.(flat chives).
I have also direct sowed diils and chervils. They are growing too.I have also direct sowed basils. They germinated and are growing but very slowly.

With thyme, sage, oregano, matrjorem, I just bought and planted established ones from nursery. I figure, I only need one plant of each. Why bother growing from seeds.
Of course, when it gets warmer I cann throw few seeds in the ground and let them grow.