Workflow: non-personalized ads, then personalized on consent?

We’re finishing implementing the code that listens to a change in user consents and recalculates the ads correctly (personalized or not).

This code needs a couple of seconds because it has to wait for the Quantcast code to finish its stuff and retrieve the cookies.

My question is: what do we do in the first seconds? I was thinking something like this:

– Show non personalized ads in the first place.
– After Quantcast has finished its stuff and my event is triggered (which happens immediately after Quantcast has retrieved its flags), we refresh the ads with personalized ones immediately if the user gives consent.

Is this the right approach?