Xiaobaitu - question for green card application for parents - th

I am planning to apply green card for my parents. In your previous post, you mentioned that it is better to submit application 3 months after entering US.
However, since my mom came later than my dad, my dad will be out of legal status if my mom reaches her 3 months.
Should I apply for them seperately or is it ok to apply for both even my mom has been here less than 3 months?
Thanks a lot for your help.