Jc is right. If you spray weeds in the fall you will have almost no problems in the spring (except new customers). Perhaps follow up with a June weed control to reduce the summer weeds like: spurge, purslane, nutsedge, and perennials like ground ivy, violets and clover. This sounds a bit like the dealer devised this program at Lesco/JDL. If you don't really have so many cinchbugs--stay with Merit or Merit with fertilizer in July.
Fertilizer will not normally hurt new seed--no worries.