Growth Edge in Link Prediction

I have 2 CSV files representing edge in social networks in 2 consecutive generations. I am trying to predict future edges.

My initial tough is to train a linear regression on the first generation with some indicators like Adar Index or Cosine Similarity between the node of the edge I am trying to predict.

I can not run all the combinations possible between 2 nodes, so I was wondering how many edges I need to add between 2 generations? Is there a mathematical pattern to the difference in edges between 2 generations of networks?

For 1892 nodes I have :
My first CSV : 12717 edges 
My second CSV : 14324 edges