Disk now if its dry enough -If its going to leech the nutrients that fast- then it won't matter when you disk - You'll still have to supplement at planting time - a Soil Test can tell you alot.

You get what you pay for in mixes. For Spring Planting - I'd suggest NOT mixing grains, corn, sorghum, sunflowers - etc with a clover plot. This because to have a good clover plot - you need to mow at least 2x per year. I'd concentrate on a clover-chicory-brassica type mix - that can be mowed. Another good mix is several clovers like White/Red/Alsike/crimson - and seed the mix 6-8 lbs per acre. Add P & K (and lime if needed) at planting.

FH