A couple of months ago, signage in existing stations that the Silver Line will service began to be updated. In some cases, the line and its soon-to-be terminus are already identified, as here at East Falls Church, which is where it will join the Orange Line.
Elsewhere, signs are temporarily covered in Metro-brown wrappings (I suspect at underground stations where the adhesive isn’t exposed to the elements). But you can just pick out the “East” part of the station name, thanks to the bright light of my camera’s flash.