First have released the Sunday timetable for the X5, which you can see here:
The Sunday service starts from 31st August and is initially supported by North Somerset Council, so use it or lose it!
The X2 and X3 will be prone to delays until Christmas, due to repair works on the Yanley Viaduct. They don't serve the viaduct itself, but traffic affected by the closures will be diverted onto roads served by these routes, causing additional congestion. There's not a lot First can do about this, which is unfortunate as they will be in the firing line from passengers affected by the delays.
To try and help speed journeys up, First have introduced their own smart card, called Touch. At the moment, they can be used to store Bristol Outer FirstWeek and FirstMonth tickets, with other zones and tickets soon to follow.