I hate to be slavish to rules. When I interview, there's this spidey sense that goes off when things don't seem right. I get lots of attempts at "bait and switch" where subvendors will submit a candidate who will phone screen (under the name of another person), then they'll send that "B-player" in for the assignment. So, you listen. But that's a separate issue.
Elon Musk doesn't sit down at his desk every day and think, "Have I made enough money to quit and travel the world yet?" Warren Buffett doesn't get to Berkshire Hathaway head office in the morning and check his portfolio and say, "Can I afford to pay off my mortgage and live off dividends for the rest of my life?"
Keep a record of your accomplishments and contributions from day one, including emails thanking you for your work, performance reports, and all positive feedback. When it's time for your performance review, if you're seeking promotion or negotiating a pay rise, you'll wish you had done it. So start now!
You just got the job offer you have been waiting for. A sense of relief floods over you that your long search may finally be over. No more uncertainty or sleepless nights. After your initial excitement wears off, it's time to seriously consider their offer. You would have to be crazy not to take it, right?