I think the update is rolling out until mid-July. So you may have to wait until then for it to offer an update. I would assume you need to have T-Mobile service to get the update. Maybe or maybe not a data plan. I purchased my phone a couple months ago and I never saw an OTA update.
If you're impatient like me. You can install the rooted ROM. It works very well. Samsung Galaxy Exhibit 4G - xda-developers