Review time and other PRs expectations

[ala85]

Hi, just a general question as I am contributing for the first time to this super interesting repository. I have created a PR a few days ago: #7136.

Do reviewers assign themselves once they found the time?
Is there a typical ETA depending on PR size?

Just trying to set expectations with myself in knowing how long a PR may take to be released, thanks in advance for your replies.