First, I am sorry about your father
I believe you are supposed to do it before the green card expires:
Conditional Green Cards
If you have been married less than two years when your noncitizen spouse is granted lawful permanent resident status, your spouse will receive permanent resident status on a conditional basis.
What this means is that the noncitizen spouse's green card will only be valid for 2 years, not 10 years. To convert the conditional (2 year) green card into a 10 year green card, the U.S. citizen or legal permanent resident sponsoring spouse and the conditional green card-holding spouse must together to petition to have the condition removed, or else the green card will expire and lawful permanent residency status terminated.
This petition must be filed within the 3 month period before the green card expires. But it looks like you can file a waiver petition -
What happens if I don't file the joint petition or the waiver in time (within 90 days of my green card's expiration)?
Your green card will be lost if you fail to file within this period, unless you file a waiver petition. A waiver may be filed even after expiration of a green card and even before the 90 day filing period. Once a CIS receipt notice is received from CIS, you will have proof that your green card is still valid for another year or until the case is decided, whichever comes first. If your case is still not decided within a year, your green card will be extended for another year and will be extended on an annual basis until the case is decided.
