A summary of my test experience while still fresh in memory.
Test Preparation: read the discover Canada 2-3 times, cover to cover. Do all these sample tests:
http://www.toptipsclub.com/Citizenship_Test_Index_KB.asp
http://citizenshipcounts.ca/quiz
http://www.torontopubliclibrary.ca/new-to-canada/citizenship.jsp
http://www.yourlibrary.ca/citizenship/
http://www.v-soul.com/
http://www.apnatoronto.com/canadian-citizenship-test-practice/
I scored 18-19 in all the tests always getting 1-2 wrong. But managed 20 at the real test. The questions at the test are way more easier than the mock tests so don't panic if you get a few incorrect in the mock tests. Make note of the 'wrongs' to revise on the day of the test.
Documents to carry with you: invite letter, Drivers license, Health card, PR card, passport (s), PR landing paper, originals of language proof.
Travel to 325 Milner: I decided to take the 'scenic' route from North York via TTC. My test was at 1:30pm so had plenty of time. I took line 1 to st.george, line 2 to Kennedy, line 3 to STC, and then the 134 bus to Progress & Milner. Approx 90 min journey, but nice and relaxing as by noon the trains were fairly silent. The bus stops right outside the test center building; hassle free travel.
The wait and pre test procedures: I waited outside the building on the benches enjoying the lovely weather. Did a quick scan of the book to go through my notes till 1pm. At 1pm I made my way up to the second floor. A pair of very friendly security men greeted me and verified the invite letter for date/time and gave me a green form (prohibition form) to fill in (Application number, UCI, First name Last name, and a signature and date). Completed the form and waited patiently in the waiting area (similar to Service Ontario with lots of seats and empty booths) till 1:25pm. A big white board had the list of documents you need to take out for the interview (2 pieces of ID (DL, Health card, PR card, landing paper, passport(s), prohibition form).
Test procedures: have your invite letter, and a photo id ready. The test admins will verify your identity and lead you into the test rooms from the waiting area. I took my bag, and documents with me and took a seat. A brief note about how flimsy the foldable side tables are, then they walk you through filling the scantrons and hand you a test booklet. Test itself was so easy that I finished in under 2 mins. Walked over to the table and handed over the booklet and scantron to the admin who will ask you to leave the room with your belongings and exit to the waiting room.
I am not sure if it was because I finished the test early, but was called in the beginning to one of the earlier mentioned booths. Very minimal questions. She asked for the three cards, passport and prohibition form; where do you work, what is your title, when did you last leave the country, how did you know the exact dates of when you left the country. She said I scored 20 in the test and that she has to complete the assessment of my file. No concerns at the moment and that I will be invited to the oath ceremony but she has no control on when it will be. I said thank you and then collected the documents and left the booth.
Overall pleasant experience. Hope this is of help to test takers on what to expect on the day off. All the best!