How do i go about purchasing a bunk bed set in IKEA do they give it the same day?

They also have a click and collect service where you buy online and pick up in store.

Yes they do

If it is in stock, you can pick it up and bring it home same day. You can pay to have it delivered to your home if you'd like.

Depends if they have any at that specific location if so they are able to bring it from the warehouse to you or have it delivered to your home.