You need to check Expert Flyer to see how many upgrade seats are still available. The number of available seats in F on Delta.com is not a good indicator of whether you will get upgraded ahead of time or not.

I've had both legs of my ATL-PIT flights upgrade at the normal window time or me so they are still upgrading when upgrade availability is there.

They may have already upgraded all the DM's and PM's and run out of availability. I cancelled my Expert Flyer subscription so I can't check on it for you, but don't be surprised if you get upgraded later today or tomorrow... but a gate upgrade is probably what you can expect at this point.

And don't expect any upgrades to clear at the window on the way back from LAS. Generally they hold for revenue tickets on flights leaving LAS and if you get upgraded ahead of time, it is usually much closer to the departure date and time.