I know we're talking Citations and not airliners, but at Alaska on the MD-80, it is prohibited to deploy the thrust reversers until the nose wheel is on the ground (to prevent dragging a bucket), and on the 717 the reversers are wired through ground shift, and WILL NOT deploy, whether you command them or not, until the nosewheel is on the ground.
At another operator where I flew MD-80s, the COM said that we may deploy the reversers when the mains are firmly on the gound, and you have "commenced nose lowering". However, like I mentioned, Alaska's prodedures prohibit deploying the reversers until the nosewheel is on the ground.
Bottom line. Comply with your aircraft's AFM, manufacturer's recommendations, or company policy. To do otherwise is asking for trouble. And usually, when you go looking for it, you will inevitably find it.