As soon as you can get a little dirt for the sample send it in, scrape the snow back if necessary and get a cup of dirt. As soon as you get the results get the lime out ASAP. It takes a few months to get a + ph result from the lime. Burn the fields off if you can. It might help to get rid of a few unwanted seeds and it will help the soil some.
Pay attention to what the other people in your area plant that they have good luck with. Usually there are two different type of food plots, spring planted (iron clay peas, lab lab, etc) and the fall plots (cereal grain grasses, brassicas, etc). I have one plot with a good stand of arrowleaf and crimson clover in it, but it doesn't grow enough for grazing until late Jan and has all died down by Aug, then I plant the grain seeds.