I wrote a little Earth Engine App where I compared the data availability of Sentinel-1C (Top of Atmosphere) and Sentinel-2A (Surface Reflectance) within the EE data catalog. This blogpost is about the code behind the App.
Since the 27th of March 2019 has the Earth Engine data catalogue one more dataset. Sentinel-2 Surface Reflectance (Level-2A) data are finally available. This blog post teaches you in one minute, how to get the current Sentinel-2 ingestion status for your country.