Next day morning after spray, the wasps inside nest may not be fully dead(it is ok, they cannot attack you any more), and some wasps outside nest try to go back nest (it might be dangerous if they attack you). So to be save, you may spay again at next 9pm, or wait few days to let outside-nest-wasp to leave nest-area forever. I use garden tool with long rod (top section is bent like hook) to remove nest.
Nest is at different place every year around my house or inside shed. Probably wasp like my vegitable garden and flowers of threes.
Thanks for advice of fake paper nest, then no new nest again.