Spring is the recommended time up north in your area. As far as mowing..1/4 acre might not need much mowing if you have a good deer population. It wont take many with the size of some of the deer I've seen up your way
Most of the plants in that mix is low growing, I would only mow if it looked like weeds was going to be a problem,,Mid-summer or so. It is optional to broadcast desired Brssicas onto the established Premium Perenial in late summer/early fall for additional fall forage.
It also needs lots of fertilizer...300lbs of 13-13-13 or equivalent per acre.
1/4 acre will need around 2 to 3lbs of seed.
Hope that helps some...just my opinions