I'm not sure where you live, but I do a pre-emergence spray around mid to late Feb. I don't use anything fancy just 2-4-D weed killer. Then again in April-May before I turn the horses out on it. Check with your local NRCS office for what would be the best chemical and time frame for your area. I'm sure there are better pre-emergence weed killers out there.
Just an FYI, I've tried the dyes you can put in the sprayer to mark where you have sprayed and didn't think they were worth the money. If someone tries to talk you into it, think twice. I find it better with a small sprayer to just have someone help you by standing in the line, or mark it with a brightly colored cloth. I've wasted tons of spray by losing track of where I had been