I was greatly surprised to receive notice on March 26th to come and take the Citizenship Test on April 15th! My eCas was updated a couple of days later.
There were likely somewhere around fifty people taking the test with me. I passed the test with 20/20. The interview was very brief, probably less than five minutes, and the officer said my application was in perfect order and had no concerns. I had many travel dates, but had included a letter saying the dates were approximate, as well as scans from all pages of my passport, with the application. This apparently helped, as the officer didn't even look at my actual passport really. I also brought some original documents with me to show them (e.g. diplomas, tax documents, etc), which they seemed to appreciate, but didn't really require. They said the Oath of Citizenship is usually scheduled within 2-4 months, but specifically mentioned it could be as soon as a month from now, and pointed out a month would be mid-May. They said it all depends on how many applicants are ahead of me. I don't know if they say that to everyone, or if it was specific to my case, and whether or not it's some sort of hint...
There are no updates to eCas yet, and I understand eCas may not update again until after I get the invitation to the Oath of Citizenship, if it even updates again at all.
My timeline is below.