As a little boy my grandmother taught me that peas were to be planted on St. Patrick's Day.
Some years it's 65 degrees and sunny and others the ground is still covered in snow. Regardless, my peas are planted on March 17th. You don't mess with grandma's advice.
The biggest risk of starting early is digging the garden before the soil is ready. This year I can almost guarantee the garden isn't ready. If the soil sticks to the shovel, it's too wet. Turning over the garden before the ground is ready will destroy the soil structure and make the rest of the season a chore.
If it's too wet I'll just get a couple bags of compost and throw it on a bed. The seeds can go right into the compost and will sprout when ready.
Regardless of the weather, the peas are soaked overnight the day before planting. They swell to three times their size and will germinate more reliably this way.
If the garden is buried under snow, I'll plant the pea seeds inside in peat pots. The peat pots are then put in the ground when the garden is ready. Peas don't like their roots disturbed, the peat pots are planted in the soil and will rot away during the season. Sometimes the seeds have already sprouted when planted, but most of the time they haven't yet.
I've done some experiments with peas, planting them in standard six packs and transplanting them into the garden. They don't like it but by the time they flower and put peas on they are only a little more than a week behind direct sowed seeds. It's a way to lengthen the harvest.
It might seem a little crazy to force an early planting of peas, but the fun of following a gardening tradition can't be beat.