(1) Simply inscribe your knowledge of any large scale events (disasters, discoveries, etc etc) over the next six months (there should be at least one memorable example) into a text file.
(2) Encrypt said text file.
(3) Give text file to a custodian. I sure Art Bell would volunteer, he’s very interested in time travel.
(4) In six months time give Art the encryption key and he can reveal what you said.
It doesn’t affect any timelines for that covered six months.
Art can’t peek, even if he wants to, which he probably would.