How long does it take for a food plot to grow?

I've never planted one before as we have always hunted woods prior to this new lease. Got a bit of a late start and just planted almost two weeks ago. I planted two 1/2 acre plots with wheat, rye, and oats and was wondering how long it usually takes for the plot to grow in strong because I probably won't be able to go check on it until opening day. Thanks in advance.