So if we secured a GM ticket, do we need to request a refund for our purchased ticket now before the deadline or do we have to do it when we arrive and pickup our GM ticket?
By "ticket" I bet you mean "badge."
You are correct
If you receive a GM badge before the shipping deadline, your badge will be refunded automatically. After the deadline, you will need to take your badge to Customer Service to have it refunded.
Also, note that GM badges are distributed to EO's, and are not sent to individual GM's. Unless the GM and EO are the same person, of course. The EO has to get them from the EO/GM HQ in person.