The NUCing time can vary greatly based on brand/model, etc. Pulsars have many positives but their NUC process is very long at least on their Trail and Helion series. In comparison, the FLIR PTS NUC is about 1/3 the amount of time. You almost couldn't mess up and shoot at the wrong time with the Flir PTS, it happens so fast.
FYI, if your screen goes black after a NUC, the shutter may be stuck. If you have an option to manually Nuc the device, it often clears it up. I know this happens on Pulsar devices at times, and a quick tap of the Power button, NUCs the device, and the shutter releases.