The include-timestamp data returned by pg_logical_slot_peek_changes() is always 2000-01-01 in 9.5.1, is it not normal？
Did you enable track_commit_timestamps in the server?
If not, and it's returning 2000-01-01 I think that's a bug - it should return null if timestamps aren't recorded. (We can't really differentiate between the real timestamp 2000-01-01 00:00:00 and the case where we didn't record a timestamp, but I don't think we care about tx's generated on the second of the millennium...)