I'll retain :
- Work as a team with your players how to play time travel / paradoxes. Debate and find your way together
- When players meet a npc, ask them whether he/she met them before and whether he/she befriended with the players. Eventually causing a sanity save.
- Keep track of the paradoxes caused by the players. And sometime review them together
- Use google agenda (or similar) to keep track of the events /paradoxes. Use colors to track what is solved or not
- He had "Early" run from sJan.01 to sMar.019, "Middle" from sMar.19 to sNov.11, and "Late" from sNov.11. Mixing the stages around these dates.
Edit :
This discussion has good ressources too. (Consolidated description per room + timeline, Maps, portraits)