Yeah, for sure wait until you plant. If you put it in now it could leech thru the soil by July if you have sandy soil. Also it would just encourage weed growth which is the last thing you want to do.
Usually I put down 100lbs per acre right before I plant then I try to top dress another 50lbs per acre after about 2-3 weeks. The top dressing isn’t necessary, but it does help get a good flush of growth once the plants start to grow.