Lucky you, I still have had 0 invites. I'm at a point where I just completely forgot Mewtwo. Not gonna get it, ever. That's what I think :)
Passes went out today, but don’t give up hope. Stick to the Sponsored or Park ones:
From a Facebook Comment- READ IT;
You will have the best luck raiding in a moderately popular eligible gym that is isolated from other eligible gyms since their pattern is slightly more predictable. It is also easier to get an invite outside of the city.
Find eligible gyms in parks.
Use
https://www.pokemongomap.info/ and set visuals to S2 L13 to see EX areas. One gym in each L13 cell can get an invite. Also under visual, you should set "parks" to "show".
Find a gym inside a park. If it's slightly on the edge, you will want to confirm that it is "inside" the park according to Niantic's algorithm, so you need to turn visuals to S2 L17. If the center of the diamond is outside of the park, it isn't eligible. See the attached photo, the southern gym (gyms are orange) is eligible, the northeastern one on the corner is not.
Now for schedule.
(1) Gyms that are the "only" eligible gym in their cell do not get invites back to back. But, they don't get raids during the week before their raid, so it doesn't matter. If you can raid there, it might be selected that week.
(2) L13 cells that have multiple gyms tend to go 2 weeks on 1 week off if activity stays high. So if you know there were 2 invites in a row in a particular cell, you should raid in a different area to try to get an invite as it will probably not get one this week. WHICH gym gets selected is not easily predictable, so if there are multiple eligible gyms in the L13 cell that is "awake" you will need to hit all of them to so that you're on the list no matter which gym is chosen.
As long as you do this somewhere that is not frequented by cloud people, you should have a high chance of getting an invite. I would recommend joining the raids discord and raiding eligible gyms in the western half of the city, where the cloud does not tend to wander.