Why may be impossible to answer. Crowding comes in many variants, not always population. Swarms due to crowding is more a matter of lack of space for the queen to lay. It can be cause by the fact that the cells in the brood boxes are full with anything: eggs, larvae, pollen or nectar/honey. It's all about space. Many think it's cause by population alone but that isn't true.
Onto your queen rearing question: From egg to hatch takes 16 days. The queen cell is capped on/about day 10. Once hatched she takes 2-3 days to build-up for flight and then 3-4 days to mate. You can expect it to take another week before you will start seeing signs of a successful queen. In all about 3-4 weeks at which time you should leave the hive closed since opening it can risk the life of the new queen. Hopefully you have time for her to mate but given your location it might be close and you may want to consider purchasing a mated queen. Worse case; if you don't see capped brood before the weather turns you could merge the hive with another of your hives (if you have one).