Asking users how did you hear about us – influenced my marketing

This is a step that has been influenced by marketing people. The step is now in the middle of the user's task, interrupting them from getting a service quote straight away.

Now, because I'm trying to find the best solution both for UX and marketing, I'm trying to understand where else can I add this step? The user flow is the following at the moment: The user selects the type of service and items to be delivered - how did you hear from us screen - price screen and then finally checkout.