Best Time to Lateral Into Groups Like PJT RSSG / EVR RX

Gonna keep this brief: currently an incoming M&A analyst at a BB, and am interested in lateraling into RX IB down the line. My plan is to aim high, hit low, and going off that, top groups like PJT RSSG / EVR RX are among the one's I'll be looking at.

Basically, is there a 'recommended' time to attempt the lateral (i.e end of 1st year at my current firm) or can you lateral whenever within the first 3 yrs? How do I stay in the loop on when apps open, and to that point, do these firms even do a respectable amount of external hiring, and do they post apps somewhere or is it mostly internally done? Is networking as important, or is it more experience based? 

Who will my competition be? I'm assuming other bankers?

Thanks for any insights.