Welcome to FT, 75chalet. Delta does tend to open up award inventory as time goes in - it's not loaded in one batch but progressively.
Delta has also cut back at Orlando quite a bit - 2 years ago they had a pretty good focus city at MCO serving a lot of smaller cities; now it's primarily to the hubs and focus cities. In addition, it's on smaller planes as the 767s are no longer heading to MCO.