Hi everybody,
I want to comment my personal situation with the Canadian citizenship process after many of your comments helped me to understand better what possibilities I could face.
I live in Toronto and I did my test in Scarborough on Sep 6, I received an email on Sep 13 with the invitation for the ceremony for Oct 1. As you can see, everything was pretty fast. The problem was that I was travelling out of the country from Sep 16 to Oct 2, so I missed my ceremony. However, I sent them an email to the email address they provide in the invitation the same day, Sep 13, saying I was going to be away, I attached my ticket and itinerary, but I never got an answer or a new invitation.
After my trip, I called immigration on Oct 3 asking about my profile and they told me they never received that email I sent, or at least there wasn't a comment on my profile about it. They offered me to complete the web form, so I did. I sent them a new web form explaining my situation and attaching my itinerary and ticket. I got and answer 4 days after, Oct 7, saying that it was going to be resend to my immigration office so they can consider it.
I never freaked out about missing my ceremony or thinking that my process was going to be forgotten, they always tell you that you have a second and final invitation after the first miss, and if you give a reason, you would get a new and first invitation again. I just started freaking out because I started reading other people experiences and it took another 6 months for the second invitation, and I had planned to go away for several months during winter time, so it would cancel my plans.
Lucky me, I received a letter on my mail on Oct 24 with a second and final invitation (even if I provided an explanation) for Nov 7, after calling immigration that same morning, Oct 24, asking about my profile, and for my surprise they told me a second invitation had been sent but I hadn't received anything yet, I told them I didn't received any email with an invitation. She said it wasn't a big deal, she gave the details and date for my ceremony and said I didn't need to bring my invitation notice with me for the ceremony, but I wasn't happy because I had read on my first invitation that you have to take it with you and sign it. That same night, I received the letter on my mail.
It is very weird I received an email the first time but a letter by mail the second time.....
Conclusión: don't freak out for missing a ceremony, even with no justification you will get a new date. The only problem is if you want to travel, they just send you the notice around 2 weeks in advance.
After reading many comments and talking with friends that have friends who went through a similar experience, I can say everything is so random and every process is different. Other people with my same office took them 5 months for the second call, you never know. Just relax, and always call immigration asking for information. I was freaking out that day that I called and they told me I had a new date but I never received the email......thankfully, I received the letter after, but it is always better to be in touch so you don't miss a step on you process.
Enjoy your new citizenship!