A good time to start is a few days after the world started. You get a relocation item on most worlds that you can use in the first 24-48 hours( depending on world settings). Most people start in the first hour, but they relocate to the rim right before the relocation item expires. If you start after 3-4 days, you are not so far behind, but you are on the rim and if you use the relocation item you get even better positioning. Most people join worlds in the first 48 hours. After a week, the amount of new players joining daily is drastically reduced so the rim is established after a week. On .net or bigger servers this is not necessarily true.
"I thought rimmed meant getting restarted on the outskirts but from what you are saying the rim is actually the outside borders when the world is finished filling out" - The rim is the outside ring of the world, the villages furthest from the core at the present time. As more people join existing worlds, the rim moves further from the center of the map and what was once the rim can become part of the main core.
If you start as soon as the world opens, as a new player you are pretty much guaranteed to be eaten by the veterans, unless you join a tribe of veterans. Tribalwars is a small community and the players know that. Many people are willing to teach new guys, so don't be afraid to reach out to the top players, they will give you good advice most of the time, or they will backstab you, because ultimately tribalwars is a war game, and the politics of it are dirty.
My advice is that you start playing the casual world once you are rimmed. You get to start with a good village( the size you had it before you got nobled) and on casual worlds you cannot attack or be attacked by someone over 20% bigger/smaller than you. Casual worlds are good for learning.
Until you become good at the game, make your first village defensive. Even if people will be able to break you, sometimes they may leave you alone if they consider the losses to be too big for your village. Don't get a ton of points without troops. No one wants to hit 1k 1k defense early game for a village worth 1k points, but they will be willing to lose some troops if you have 1k 1k def and 3k+ points, so prioritize troops as much as possible until you learn how to get both troops and points at the same time. Make sure your wall is at a good level. If you are building defense, 5 levels for each 500-600 points will be enough. At 2.5k points you will have a wall of 20 or close to 20 and that's scary early game.
Tribalwars is a simple, yet complex game. The mechanics of the game are simple. Once you learn how to use scripts farming is easy, sniping/backtiming are not hard to do if your internet is good, but the politics is what complicates the game and also makes it more enjoyable, so don't underestimate the power of being in a tribe. Make sure you have allies nearby and help them when they are under attack. That same attacker that's going to take out your teammate will be coming for you one day, so better stop them the first time they throw a punch at your team.
There is another strategy you can use. Contact the top players around you and ask to be their morale basher. Attacking is more fun than being a turtle that just defends. In tribalwars, the morale system makes the small players have a big defensive buff when they are attacked by someone way bigger. That means it isn't worth attacking players under 10k points if you are at let's say 100k. That's where morale bashers come in. They are small players, with only offensive troops who make a deal with a bigger player. The big player defends them and in return, the morale basher clears targets for them that would cost the big guy too many troops. No top player will refuse a free morale basher and they will likely teach you how to play, as they need a reliable, knowledgeable morale basher.