Go ahead and plant this year. Fresh cow manure can cause problems with scab in potatoes and worms in root crops but when mixed with other soil it can be neutralized and still support many plants.  Just try to work it into the soil by turning it under and add more organic matter such as sawdust if you need to dry out soil made by mucky by fresh manure. Just think how great your garden soil will be next year with all that manure. Keep growing, Marianne Binetti