Trainline is normally 3 months in advance for “long distance” routes, but I’m still waiting on a May Manchester to London timetable to appear as it’s not been released by the train line yet. Timetables are normally set in stone around 12 weeks before travelYes booking early is best with Trainline to get the good prices, it's 6 months in advance, this morning I can see up to 10th September.