I like to clear first and buy second (in a perfect world). My world hasn't been perfect for quite some time...
Right now I have 300 daylily seedlings that I plan to plant in June (they are in the house now). A couple days ago we put down a tarp to kill the grass. I'm sure it won't kill it but there is too much other stuff in the garden that is calling, so it will have to do for now. I'm sure this new seedling bed will be a nightmare in the years to come.