[Also available on Facebook.]
As many of you are aware, a standard joint I-751 petition must be filed within the 90 day window starting 90 days prior to expiration date of the green card. You can figure out the earliest day you can file using the online calculator provided by USCIS:
The 90 day window does not apply to I-751 petitions seeking waivers of the joint filing requirement. Cases seeking divorce waivers can be filed any time after the divorce is final. Cases seeking battery/abuse or extreme hardship waivers can be filed at any time.