Clovers can be a slow grower,so don't till it under just yet,overseeding more won't hurt though,I had the bright idea of mixing corn with cowpeas last year and using a spreader to apply it,won't do that again,it was a common lookin stand of crap,If I planted it with a planter it would have tuned out better,goin to try that this year.I have had excellent luck with a mix of winter wheat and or oats with turnips it rocked and have been using it for the past 5yrs.