So you wanted wildflowers but now you're going to try for lawn? Obviously the lawn will be a lot more work..... would you consider just mowing the weeds and such that you have now and calling it done?
If you mow once about late July you will encourage early wildflowers, discourage bushes and trees, and spread the seed of whatever grasses have bloomed and set seed. Cut once or twice again in the fall to neaten it up for winter. I don't like goldenrod, so the later mowings will help control that.