For Vega, which is a telluric standard A0V star, the IGRINS Exposure Time Calculator (Version 2.11) gives the following estimates. Here we show S/N estimates for 30 & 300 second exposure times with a quad (e.g. ABBA) exposure set.
Park et al. (2014; SPIE Proceedings) find that the observed S/N is ~83% of the predicted value.