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
There should be less than 801 meteor
tiles, or the Meteor is not eligible
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
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
Drops will be stopped, tiles will be
killed and meteorite tiles will be
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