@tsarstepan,
My nephew got three job offers, took one and put his notice in. The day he was to start the new job, they withdrew the offer because of loosing a contract. Fortunately, one of the other jobs was still open and a good one.
When I left a job I've been asked why I didn't post notice. I ask them, if you were to fire me, how much notice would I get,and I'm always told, "None."
I tell them to consider themselves "fired". I do design work, and I can be picky about who I work for.