The rule is, the home must have been your primary residence for at least 730 days of the last 1826 days you owned it. You can only claim the exemption after two years have passed since you sold the last home that qualified for the exemption, and you actually took that exemption.
So if you closed in sept of 2020, I would suggest you wait until Sept of 2022 for the next one. Keep in mind the IS counts days. So if this home was your primary residence for 729 days, you don't qualify for the exemption. Also, the date that prior home stopped being your primary residence and the date the new home started being your primary residence can't overlap, and they can't be the same date.
