Extent of knowledge of potential future gamma ray bursts
Although not being an expert on the field, I found a multitude of studies dealing with events which may be used as indicator that a GBR is about to happen somewhere. Research on GBR precusor events range from smaller gamma ray precursors, over gravitiational waves, to thermal signatures, and neutrinos:

Sarp Akcay: Forecasting Gamma-Ray Bursts using Gravitational Waves (2018)
Thomas Koshut et. al: Gamma ray precursor activity as observed with BATSE (1995)
L. Piro et al.: Probing the Environment in Gamma-Ray Bursts: The Case of an X-Ray Precursor, ... (2005)
E. Troja,  S. Rosswog, and N. Gehrels: Precursors of short gamma-ray bursts (2010)
Frédéric Daigne, Robert Mochkovitch: The expected thermal precursors of gamma-ray bursts in the internal shock model (2002)
Coppin, Nick van Eijndhoven for the IceCube Collaboration: IceCube search for high-energy neutrinos produced in the precursor stages of gamma-ray bursts (2019)