Hey Aryan161,
usually ppl get their PER/NER mail 20-30 days after DD encashment.
CIC encashes DD after the completeness check is done (if applicant have provided all the papers required) and then proceeds with applicant's assesment against FSWP criteria (sufficient points, working experience, funds, etc).
PER/NER is issued based on the results of this asessment.
Hope this helps.