Please explain how you could end up with more than 600?
They'll only roll over once this month and once next month, so unless a person does new listings they can't go over 600 if that's how many you started with. The idea of the longer cycles this month is so that they never relist twice in the same month in the future, as they used to do in months with 31 days. Some of mine will relist on 31st of this month because they seem to have only started the new system after they rolled over on the morning of the 1st, but in future this should never happen.
If you sort by ending soonest you only need to end the ones that are due to roll over if you don't have enough free listings for them, or if you want to give another listing a turn instead.
