Set ad position after the data is loaded



I’ve found the ad position could be set both on Server side (mopub setting UI) and Client side (code).
Is there any way to change the ad position after my mopub adapter is created?
Can I set moPubClientPositioning.addFixedPosition(position); after my mopub adapter is created.
Because there is some data I need to get from server side.
I only can decide the ad position after data is loaded.
What should I do ?