Discing disrupts existing weeds. The amount of disruption depends on how much you disc. At the same time, it brings new weed seeds into the germination layer starting new weeds. Under normal conditions, none of the seed you plan to plant require discing. Glyphosate (assuming that is what you are spraying) has no residual soil effect and does not effect seeds. It only affects actively growing plants.
It is hard to say without a picture, but you might want to consider an approach where you spray the weeds, wait an hour or so for the gly to become rain fast, and then surface broadcast your seed. If you have a cultipacker, I'd go over the field with that after broadcasting the seed.
There are soil conditions and such where discing is necessary but that is the exception not the rule for the seed you are planting. Check out some of Crimson N Camo's throw and mow threads for more details.
Help the deer without hurting the soil...
P.S. If you don't have time for the Gly to dry or don't have a cultipacker, broadcast the seed first and then spray the gly.
Thanks,
Jack