Btw, when I saw the status change with test invitation, I called IRCC to ask about my address on their file(I had an issue with incorrect mailing address that was taken from my PR application from 6 years ago). The agent checked my file and told me to write down test center address in case I don't receive regular mail. He sent me an email with a list of required documents for an interview and told me that I can go directly to the test center if I don't receive a letter(I had less than 2 weeks between status update and test date).