The only reason I'd do it now, is if I knew I wouldn't have some free time to get it done for the next month.

I believe there will be plenty opportunities ahead. I'm south of you a good ways and its very common to have below freezing mornings ideal for frost seeding, through the month of March.

The main advantage to seeding on to frozen ground, is the soil is "honeycombed" which draws the seed into the soil, creating the good seed to soil contact. Plus I don't like walking through greasy mud any more than I have too.

Ultimately, you could seed your plot anytime this month with or without frost, and you'd still be fine...as long as rains come in a timely way throughout spring, and the rain wasn't in the form of a deluge