Here is the first thing you need to do when you get your PER. Since your travel to Senegal is AFTER you submitted your application, you should update NDVO of your travel to Senegal and change of job soon after you get PER. After NDVO acknowledges the updates, it will be upto NDVO to decide what to do with your application.
And about the time point, what I am saying is, it doesn't matter when you move to India again. As per the ministerial instruction, decision on your application will not be made (that is visa will not be issued) if it hasn't been 3 months since you left Senegal. It is upto NDVO to decide if they will begin the processing after 90 days or start processing early and only make the decision after 90 days. Since there really hasn't been any other case like yours, you can only wait and see what happens (any prediction would be assumption).
So, it might be best for you to move to India in 15 days, and then update NDVO of your travel to Senegal, start and end of the job in Senegal, and then travel back to India in the same update so that the VO knows exactly when you left Senegal for good. NDVO will then do whatever it is instructed to do in situations like these.