The impression is fresh for a while. What is the first thing you do?
Do you discuss it? Do you write some kind of review for yourself? Do you explore professional reviews/analyses instead to compare the perspectives? Do you give yourself some time to form an opinion? Do you do something else?
Write down what date I finished it (so that I have the record of it), and write down any thoughts about the overall book.
If I’m reading the book on an e-reader then make a reminder to sync my notes and highlights (so that they aren’t just on my e-reader).