For annual nutrition and attraction you need to consider planting a variety. Arrowleaf, Crimson, ladino, and red clovers all peak at different times and will provide for turkeys nearly year round.
you can plant the crimson and arrowleaf together (they are better for full sun/drier upland sites)
and ladino and red clover can be planted together as they handle shadier/moist sites better.
You can't establish a food plot in just a month and certainly not by April as killing frosts are the issue. These clover varieties should all be planted in the fall. But you are absolutely on the right track. There is no better planting for turkey than clovers. They provide green browse and attract the insects that poults need in their first few weeks of life.