Master Chronology
Based on the link provided by Mark Horsfall, and the information Paul Westermeyer has compiled and compared in the linked article, the following information has been derived:
Sources
The three primary campaign settings for D&D are Greyhawk (GH), Forgotten Realms (FR), and Dragonlance (DL). These three have more material published than the other settings, and include the majority of the cross-time references. (Which other settings are: Spelljammer (SJ), Maztica (MZ, part of FR), Al-Qadim (AQ, Also part of FR), Mystara (MY), Ravenloft (RL), Planescape (PS), Birthright (BR), Athas (AT), Red Steel (RS), Odyssey (OD), Lankhmar (LM), Eberron (EB) and Conan (CO).)
There are four additional primary sources for chronological cross-time points: Spelljammer, Planescape, Ravenloft, and Dragon Magazine (DM) articles written by Ed Greenwood himself.
Please note that there are some contradictions in sources, so precedence is given to authors with more published works and to sources based on Spelljammer (as it is specifically designed to cross-bridge the settings) as well as the Big 3 (FR, GH, and DL).
FR/DL cross-time link
Based on comparative information from SJ, FR, DL, RL, and PS the best cross-time linkage is:
1361 DR <-> 358 AC
The RL data contradicts itself, weakening it as a source, and the PS data fails to trump the SJ data.
GR/FR cross-time link
Based on data from FR/RL/GH and DM sources the best cross-time linkage is:
1361 DR <-> 581 CY
Note that the DM articles were written by Ed Greenwood about the wizards Elminster, Mordenkainen, and Dalamar meeting in his home on Earth to discuss the magical affairs of Faerun, Oerth, and Ansalon with reference to various famous wars and other events; and as such provide a strong primary source for cross-time linkages. As such, the dates of these articles can be used to provide an Earth-time linkage as well, should such be desired.
Other cross-time links
Linkages to other settings frequently fall back on the publication date of the earliest release of said setting, combined with in-setting references, or lack thereof, to determine dates. For detailed reasonings, check the link if available - and I have saved a copy in case the link goes down.
Calendars
After all is compared, the following calendars can be synced, with confidence:
- Forgotten Realms: Dale Reckoning (DR), Shou Lung (SL)
- Greyhawk: Olven Calendar (OC), Common Year (CY)
- Dragon Lance: Ansalonian Calendar "Alt Cataclius" (AC)
- Spelljammer: Time of Unity (TU), Anno Vulkarus/Promo Novo (AV), Astromundi Chronos (AstroC)
5043 OC = 581 CY = 358 AC = 1361 DR = 2611 SL = 465 AV = 856 TU = 9/1299 AstroC
This corresponds roughly to the 1990's on our Earth, for those interested.
The Cat Lord is not a deity
Until the 5th Edition Volo's Guide to Monsters, none of the many variations of "Cat Lord" in D&D canon rose past rank 0 "quasi-deity," and even that was only a sidebar'd suggestion in the Epic Level Handbook.
In terms of religious veneration of the Cat Lord, the best attestation I could find came from Dragon Magazine Compendium, in which the tibbits are also said to follow the Cat Lord. Here, the Cat Lord is identified merely as "a powerful creature" and it's noted that the tibbits have no organized religion surrounding her, viewing her as more of an older brother figure and spiritual protector. This includes no details about any religious practices.
...but the tabaxi have other gods
The gods of the tabaxi, at least in the Maztica setting, are Tezca, Nula, Azul, and Zaltec.
Tezca is a chaotic evil solar deity. He desired fresh human hearts as sacrifices. His faith is a brutal one; each day at sunset, his priests congregate to offer the fresh heart of an unfortunate victim to ensure that the sun-god shall show his face again tomorrow. His faith is related to warmth, life, and power over fire.
Nula is a chaotic neutral goddess of wild beasts, a demipower whose influence is growing slowly across the Maztican continent. She is invoked by hunters and those who fish, leaving gifts of seed and bone in the wilds for her to know she has been called upon. Primarily depicted as a monkey, she has lesser aspects representing many other animals of the wilds.
Azul is a lawful evil god of water and rain. Often the first deity enshrined and venerated in new territory (to ensure the rains favor this land and will provide for its people), Azul watches over all bodies of water, from the smallest streams to the mighty ocean, and even the very rare (in tabaxi territories) snowfalls. His priesthood keep themselves scrupulously clean with baths and pumice stones. Foul sacrifices are performed to him in the spring to ensure a prosperous wet season.
Zaltec is a chaotic evil war god, a vicious deity symbolized by skulls, hearts, blood, and jaguars. Tabaxi who have fallen under the sway of a tabaxi lord (a related creature) tend to worship Zaltec. He is venerated by fresh hearts on his altar, blood spilled in battle, fasting, and ritual scarification. His priests wear black robes, wash their hair in the blood of their victims, and spike it outward in garish diplays. What that might look like, who could say.
Beyond that, though, there is nothing official about the Cat Lord's religion
...because, as noted above, it simply doesn't exist. "Cat Lord" is a well-worn trope in D&D, having appeared in some form in short stories (a group of them appear), novels, the 1st Edition Monster Manual II (the original, a male), Planescape (the second, a female), the Epic Level Handbook (a 37th-level shapeshifting rogue, male) and elsewhere on and off. Until Volo's Guide, however, none firmly attributed deity status to a Cat Lord, and no source that I've found suggests any kind of open worship.
That doesn't mean you can't borrow some...
There are other feline deities, of course - you can look into Ferrix, goddess of weretigers; Bast, a vengeful Egyptian tutelary cat goddess, and Sharess, a Faerunian demipower of cats and hedonism. Any of these might provide a reasonable model for a Cat Lord religion, if that's what you're after.
I hope this has helped.
Best Answer
It did originate from the cat people themselves, in fact different types of them (leopard men vs jaguar men) pronounced it differently according to an article in Dragon Magazine issue 93 in 1985 and later backed up by the 'Monstrous Manual" published ironically in '93. Its also made clear that the tabaxi language is a precursor to the payit language, but the language of the human tabaxi tribe was unrelated, they only took the name.