I'm somewhere around 6-800 days and im so ready for the white walkers, is there a specific way I can trigger their invasion? same with the targaryens, I know both these factions are supposed to invade westeros at some point, im just not sure when or how
Targaryens invade around day 400 and I believe the WW invade after you do the quest line that begins in white harbor tavrern.
Hope this helps. :)
Wight Walkers invade at Random, Targaryens ONLY invade after Varys questline is said and done.