Time Requirement for Meteors?
Taken from an answer to this question:
During the day which consists of 15 minutes, when a shadow orb has been smashed that has caused no other events there is a chance of 1 out of the 50 on every second that a meteor can be enabled.
If a meteor has been configured it will spawn in the middle of the night which consists of 9 minutes, so it will spawn 4,5 minutes into the night. It spawns as follow:
There must be an active player (on a server), so that it is aware of the Meteor drop.
There should be less than 801 meteor tiles, or the Meteor is not eligible to spawn.
The meteor will land within 672 blocks to each side of the spawn, so that it's close to the player.
A maximum of 100 attempts will be made to land the Meteor in a place where it is eligible:
It may not land 50 blocks close to the borders of the map.
It may not intersect with a Player, a NPC or a Chest.
The top most solid block will be tried.
Drops will be stopped, tiles will be killed and meteorite tiles will be placed.
So there is no time requirement - if a meteor has been chosen to spawn, it will spawn in the middle of the next night. It seems you've just gotten unlucky with your meteors.
All credit for the research goes to Tom Wijsman
There is no set amount of time. Some people have it happen immediately while others have had to wait a few in-game days (3-5) for one to show up. In-fact, while rare, you can get a meteor to show up with out even smashing an orb. (as happened to me on my new map where I have done nothing but built houses).