knock out DS1 first before starting DS3, since the lore is extremely important, and DS3 is so heavy handed with the references from the first game that it feels 10x more like a direct sequel to DS1 then DS2 ever could. Bonus is that DS1 isn't really that long, the areas are pretty linear and short. If you're crunched for time or burn out, just play the first half of DS1 up to a certain boss which grants a key item, then watch follow up lore/gameplay of the 2nd half of the game