I'm expecting we won't see a trailer til around the SDCC time frame. I would not be surprised if they dropped the trailer there for the crowd and also show the first two or so episodes during the event to start to get the buzz up even more. FX doesn't do trailers for their series super early, it's usually within the 90 day window, or even less, closer to 60 and below.
SDCC is quite close to the release date though, so I wouldn't be surprised if we see something more substantial earlier as well.