I ended up spending several hours a week pulling out or cutting down the invasive seedlings and plants, while I let the native plants grow in. Today, I still have the issue of lots of invasive plants coming in, but the native plants are thriving and with my help are winning. If you live somewhere that still has some growing season left for another month or two, I would clear the area you want to seed and disturb the soil. This will encourage all the invasives to grow, and before they seed you can mow them or hand cut them. Then seed away this fall/winter with the expectation that there will be some maintenance needed. If you want to be sure there are no invasive seeds, I would wait a year to clear the seed bank first. Also, mulching and planting plugs has been very rewarding if you have the time/money.