My preference is somewhere in between. Unless you know something more specific about the age of the queen cells, assume the old queen swarmed about the time the queen cells were capped (this does vary, but if that’s all the information you have, then you make your best guess). So, swarm date plus 8 days = approx date of virgin queen emergence. Then I would add another 14 days to the date of emergence for her to mate, mature, and start laying. This 14 day period can vary as well - shorter if good weather, longer if bad weather. So, at approximately 22 days from the date of the swarm is when I would check for eggs and larvae.
Keep in mind that it is best to avoid hive disturbance during the queen mating and maturity time period.
Also, before queen emergence, while the queen cells are capped, I would suggest that you go into the hive and reduce the number of queen cells down to 2 or 3 healthy cells that are fairly close together on the frame. By doing this, you are minimizing the chances of a cast swarm.
Best of luck with requeening!