Time to put on your big girl pants. We're leaving the physical universe behind and crossing the Veil into the Maelstrom. That involves finding a nearby portal - the Veil is peppered with the things, each one leading from a different place and time in the mortal realms. They shift and change like they're living things. Some grow old and collapse; new ones are "born". It's not controlled by the gods. It's just a universe thing.
From the Maelstrom side, you can't see clearly through a portal so it's always a leap of faith when your Telemsa opens one and you step through. Sure, you can get an idea of where (and when) you're heading, but the exact details of the situation on the other side? Not knowing everything is half the fun, or so I'm told. I've appeared in the middle of an active war zone, so personally I'd rather know. Sadly, that's not an option. Even the gods don't get a perfect view through the milky barrier of the Veil.
Time in the Maelstrom flows relative to the realm you're in, or on your own internal clock if you're travelling between Maelstrom realms. Traveling the Pulse clouds and currents isn't like flying in the mortal realms. The realms are spaced out (in every sense of that phrase) and your Telesma can sense which one's where, but you couldn't draw a map or measure distances. The Maelstrom would drive cartographers and surveyors mad.
As for the god realms themselves, there's one for each pantheon of gods from human history. That means the ancient gods, like the Norse on the world tree Yggdrasil. It also means modern gods, like the Realm of the Archangels. And there are homes for gods from later parts of the mortal timeline too, like the Realm of the Pure Mages. Don't forget that gods have an agreement not to cross the Veil, but even ancient gods can affect mortal realms across the whole of time by hiring heroes to help them out. I mentioned Athena and her Garden world in MR54, and that's a good example.
Finally, don't be surprised if some god realms aren't exactly what you're expecting.
Example: The gods of the Aztec, Inca and Mayan people grouped up to create a super-realm. They call themselves Inktans now and their clubhouse is a pretty amazing place if you don't mind blood-soaked altars. They're not bad gods, but tend to be influenced by the element of Dark which often comes with a mind-set of "the means justify the ends" and "acceptable losses" to get what they need. With the Tempest, there's a lot of blood on those altars.
Another example: Ra convinced most of the Egyptian gods to modernize, and the new techno-Egyptian pantheon is super slick with its ultra-modern pyramids and hard light tech. Set got pretty angry about that, preferring the old school slaves-and-sandstone style, so stomped off and created his own realm - Xaos. Ra issued a takedown order on him and a group of demigods carried out the assassination, leaving his realm out on the peripheries of the Maelstrom. Nobody's betting against Set making a comeback some time, and under the Tempest threat I reckon Ra will be pleased to see him.
Rules Of Their Own
For the most part, god realms are created to feel familiar to the time a pantheon had its heyday. Mount Olympus is much like ancient Greece, and so on. Most of the rules of the mortal realms apply. Once you get to the realms of great spirits and other odd corners of the Maelstrom, all bets are off.
Example: The Great Spirit of Red created the Red Realm and it's an abstract collection of everything the color stands for - love, rage, danger, fire, sunsets, boldness, lobsters, and so on. It used to be a neat place to visit. Then the angry side took over so Red left to start a new realm and the various gods decided the old realm would be the perfect place for a rust-covered nightmare of a high-security prison. I wouldn’t recommend taking a vacation there now. The lobster fiends will eat you for breakfast.