WDW to TPA How much time to allow?

[Rpsemont]

In shopping for best fares, it would be most economical to have DD and BIL fly into TPA arriving at 4:40 PM. We would drive over from WDW to pick them up. I realize this is going to put us right in the height of rush hour. So, what time should we leave WDW to get there for 4:45 and how much longer will it take us to get back? Is it worth it to try and stay off of 275? We remember that to be a bit of a parking lot alot of the time last year.