Please be patient people. Also, try to avoid the urge to message me chasing for the invite. Some last night sent multiple Live messages, which slows me down a bit. A couple of gamers sent around 10 further messages. I generally do them within 24 hours, but from then it is up to MS. "bumping" your message actually puts you further back in the queue, due to Xbox live moving threads to the top of the list. I work from the oldest first when adding. If I haven't messaged you back in 48 hours, give me a nudge.
Also be aware that the invite process is easy, but can be a little time consuming when I gave hundreds to do. Last night it took me over 1 hour just to send the "done" messages.
So, in conclusion, yes everyone can have an invite. But, the instructions must be followed, or else I genuinely won't notice you appearing in my activity list.
Lastly, I get quite a lot of people asking if I want to game with them. I'm happy to game with anyone, but if I forget to reply, it is because I have had tons of messages. Also, if I send a "done" message, and you want to reply, could you give it an hour or so? Just to give me time to churn through the requests.
Cheers people.