The spec sheet for the 920th AC&W Squadron crest was photocopied from the original on file at the USAF Historical Research Agency, Maxwell AFB, AL. It gives the official description, blazon, and significance for the emblem, and lists the date of approval as 26 Sep 52. It also provides a very short history: "The 920th Aircraft Control and Warning Squadron was constituted 15 Oct 51 and activated 27 Oct 51 at Grenier AFB, Manchester, NH." During these early years, many of the units were activated at one base and then transferred to another. I don't have the date of transfer, but it seems likely this emblem was approved for the unit while it was still located in the US. It is well documented that the 920th was operational at McAndrew AFB in Newfoundland in 1953 and 1954. Activation always preceded "operational" status - sometimes by several years. In fact, sometimes units were activated (which is mostly a paperwork thing) which never become operational!
In short, this crest was approved for the 920th AC&W Squadron prior to the Squadron being sent to Newfoundland.