yes it is possible

I think that it is very possible for USCIS to work on your case. They don't really process cases accrording to the process date. For example, my I-485 was submitted last sep. but I know for sure that they are processing my I-485 because they sent me RFE for my I-485 and asked for fingerprint. However, they will not be able to approve my case until my PD became current.