You will need a size 40 Palace and a bunch of similar sized clan mates.  And then there is not much to do there.

It helps to operate a youtube channel because you can encourage your followers to send attacks your way.

You can visit much earlier when the short, one hour, events are on.  The point then is to snatch just a tiny number of points for kills and this will get you into the rankings for your league.  But snatching those tiny number of points is not particularly easy or fun.  There are probably better things to do with your time.  If you want to try that you don't have to wait.  Make a couple of visits just to get the feel of the place and to see what people do there.  After a couple of visits you can try your hand at the snatching a few points during a short event idea.

To summarise what John said, the simple answer is never. By the time you reach L40 the current level L40s will be a million times more powerful because that's the only direction development of this game that takes place now.

Exactly so.

I have just watched two towns from two different clans from two different kingdoms reinforcing each other (rss?) and nothing to suggest they have an alliance. It used to be possible to guess which clan member was sending high level troops to reinforce another clan member, .... it would seem it has just got a whole lot more complicated.