Typically, they will open in the April/May timeframe; however, your MoC's can publish their requirements 'when' they like. I advise my students not to sacrifice quality for promptness, especially this early in the 'new' cycle. Most due dates for the nominations will be in the Sep - Nov timeframe, so you may be 'missing' important items from the late spring and summer that you would want to provide through the applications. A few MoC's encourage early submissions by a few weeks, but a few months is likely way too early. I recommend that you 'hold your fire' until late July or early August. Good luck!