D&D canon has demonstrated numerous times that the various campaign settings are in fact, connected to each other. Powerful beings from Greyhawk, Forgotten Realms, and even Athas have found ways into other campaign settings in the D&D stable of worlds. (Even Earth is included in the list of alternate Primes visited, interestingly enough.)
Irrespective of the means used to cross from one campaign setting world to the other, are there any solid timeline references, correlations, or overlaps (specific dates or even a range of dates) where it can be demonstrated what year (or range of years) a cross-setting traveler would end up in when moving from any given setting to any other given setting?
For example, it has been demonstrated that both Elminster and Mordenkainen have traveled to each other's home Prime, as well as to Earth (apparently during the 70's - 80's). This provides a basic frame of reference, however they both lived rather long lives, and thus only provides a common range of dates that overlap in Oerth and Abeir-Toril; namely the date range of the span of their lives, or at least after they both reached a certain level of power.
I am open to timelines from any edition of Dungeons and Dragons, and all official campaign settings in the D&D stable (Spelljammer, Maztica, Mystara, Al-Qadim, Ravenloft, Planescape, Greyhawk, Forgotten Realms, Birthright, Athas, Dragonlance, Red Steel, Odyssey, Lankhmar, Conan, and so forth). Also, as the presence of our modern Earth is explicitly included in D&D canon, using Earth-based cross-references to multiple campaign settings in order to establish a linkage is also acceptable. I would prefer to avoid time travel, unless said reference manages to establish a firm date link.