Installation of a MIP Timing Detector (MTD) at the CMS detector will introduce new capabilities and will allow precise timestamp assignment to traversing charged particle up to pseudorapitidy of $|\eta|=3$. Targeted timing resolution is $40$~ps per track, which will help reduce the pile-up conditions expected at the High-Luminosity LHC. The endcap region of the MTD, Endcap Timing Layer (ETL), will be instrumented with silicon Low Gain Avalanche Diods (LGADs), covering the pseudorapidity range $1.6<|\eta|<3.0$. Progress on characterization of LGAD sensors for the ETL will be presented.