Nothing at all, but there is no set pattern at all. By looking at the actual updates or GUs on GC key and tracker, all of us are just making assumptions. I know people who had nothing on their tracker and 1 fine day everything got updated and the next day they had their email.
In my case, final thing to get updated was Background check “Completed” on March 3rd and nothing since then.
Day before yesterday, I had a word with some immigration lawyer and he told me that he has clients whose Aor was late December and have got their portal emails a month ago and he also has some clients who are waiting for more than 8 months.
He suggested me to not make any assumptions lookign at the updates in the tracker, cz somewhere we all know that these are not accurate.