I dunno. I think we have to be clear on what herbicide it is we are spraying. I know, here it's assumed to be glyphosate? If it is, glyphosate is a contact herbicide absorbed thru plant cell walls and stoma (respiration holes in the leaf) into any green plants vascular system. Glyphosate is reported to be inactivated in the soil upon contact with it. Effectively, there is no soil residual. Seeding before, during, or after presents no problem as there is no plant transport mechanism - only a seed with it's coat still intact. If you seeded and then sprayed sometime after seeding it is possible to wipe out your crop. The key there is understanding the time any particular species needs to germinate.
I suspect we don't much use them here, but there are pre-emergent herbicides applied to the soil ahead of planting that might stop a germinating seed. It depends on the herbicide and the seed. Here and there I hear of simazine being used to control grasses in some crops. And these pre-emergent herbicides normally have a residual - an effectiveness at stopping the specific weeds from germinating for a period of time.
It goes on. Point being you need to know your herbicide and the weeds it controls to know the answer to the original question which simply was, I think, can I spray and seed on the same day. Spray what and seed what might be the answer.